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Biomedical subjects

M Vega

Publications and source records attributed to M Vega.

At least 55 records · Page 3Linked to original sources
PubMed1998

Determination of copper and arsenic in refined beet sugar by stripping voltammetry without sample pretreatment.

Copper and arsenic have been analysed in refined beet sugar at the microgram kg-1 level by anodic stripping voltammetry (copper) and cathodic stripping voltammetry (arsenic) in the differential-pulse mode (DPASV and DPCSV) at a hanging mercury drop electrode (HMDE). DPCSV measurements of arsenic are based on its accumulation onto the HMDE as an intermetallic Cu-As compound followed by the reduction of As0 to arsine in hydrochloric acid medium. Measurements were directly carried out on untreated sugar solutions. The performance of the procedures was compared with electrothermal atomic absorption spectrometry and stripping voltammetry applied to digested sugar samples, and showed in general better accuracy. The procedures were applied to the determination of these toxic elements in commercial beet sugar samples of concentrations below 50 micrograms kg-1 copper and 15 micrograms kg-1 arsenic were found, which are much lower that those allowed by the current regulations.

Arsenic↗
PubMed1998

Luteal leukocytes are modulators of the steroidogenic process of human mid-luteal cells.

Flow cytometry analysis of luteal cells revealed that an important proportion of these cells are leukocytes. The percentage of leukocytes was higher in the early (42 +/- 4) and late (35 +/- 3) luteal phases than in the mid-luteal (24 +/- 2) phase. However, the proportion of macrophages did not differ between the luteal stages. The flow cytometric properties correlated with cellular size and granularity were not reliable as discriminators of luteal cell subpopulations. Therefore, to assess the contribution of luteal leukocytes, these cells were completely removed from luteal cell suspensions (total cells), by a negative selection procedure (immunomagnetic separation). The functional role of leukocytes in mid-luteal steroidogenesis was assessed, in total as well as leukocyte-depleted cells. Progesterone production was found to have increased 2.2-fold in leukocyte-depleted cell cultures, in comparison with total cells under basal conditions. However, the response to human chorionic gonadotrophin (HCG) was 36% lower under the latter conditions. Oestradiol production was not significantly modified under basal or HCG-treated conditions. In leukocyte-depleted cells, the concentration of interleukin (IL)-1beta decreased 5-fold in comparison with total cell cultures, suggesting that leukocytes are the principal source of IL-1beta. In summary, the results of the present investigation suggest functional interactions between the immune system and steroidogenic cells of the human corpus luteum.

Adult↗
PubMed1998

Regulation of human luteal steroidogenesis in vitro by nitric oxide.

To evaluate the effect of nitric oxide (NO.) in human corpus luteum (CL) function, we investigated the expression and the presence of NO. synthase (NOS) in the human CL and the action of NO. on the in vitro luteal steroid production. The expression of endothelial NOS (eNOS) in early, mid-, and late CL was assessed by reverse transcriptase polymerase chain reaction (RT-PCR) and the immunohistochemical study was performed in human CL histological sections by using monoclonal antibodies (MAbs) against the distinct NOS isoforms. In addition, seven human mid-CLs were enzymatically dispersed, and the cells were cultured with NO. donor compounds. Steroid production was measured in the culture media by specific radioimmunoassay. The results show that the expression of eNOS was highly detected in mid- and early CL, and to a lesser extent, in late CL. Meanwhile, the immunohistochemical study indicated that both isoenzymes of NOS were expressed in mid-human CL, eNOS being the more abundant isoform present. On the other hand, functional studies showed that NO. donors (L-arginine [L-Arg] and sodium nitroprusside) elicited an inhibitory action on steroid synthesis, preferentially on estradiol production by the luteal cell cultures (p < 0.05). In conclusion, the NO-NOS system is present in the human CL, and it may serve as a modulator of the in vitro human luteal steroidogenesis.

Adult↗
PubMed1998

[Intra-arterial fibrinolysis in acute thrombosis of the basilar artery].

INTRODUCTION: Ischemia in the territory of the basilar artery presents with a variable clinical picture of hemiparesia-tetraplegia, progressive deterioration of level of consciousness, irregular respiration and apnea leading to irreversible coma and death in between 75% and 86% of cases. The usual treatment is supportive. CLINICAL CASE: We present the case of a 49 year old woman with acute thrombosis of the basilar artery and a progressive course leading to coma. No bulbar lesions were seen on the CT scan done in the Emergency Department. Thrombosis of the basilar artery and permeable bilateral carotid systems were shown on arteriography. There were no contra-indications to fibrinolysis. Following local fibrinolytic treatment with urokinase the patient had full recovery from her neurological disorder and no sequelae. The basilar artery remained permeable six months later. CONCLUSIONS: Emergency treatment with cerebral intra-arterial fibrinolysis within the first six hours, in a case of neurological deficit progressing in the basilar artery territory, with persistence of brain-stem functions and no signs of decerebration (provided there are no contra-indications to fibrinolysis and the initial cerebral CT scan shows no bulbar lesions) may save the patient's life, with total or partial recovery of brain-stem function.

Acute Disease↗
PubMed1997

The epidemiology of cutaneous leishmaniasis in subtropical Ecuador.

An epidemiologic survey (n = 466) was conducted in an area of subtropical rainforest in north-west Ecuador with the following objectives: (1) to determine the prevalence of cutaneous leishmaniasis (CL), (2) to identify the Leishmania species causing human disease, (3) to investigate the major clinical manifestations of leishmaniasis, (4) to study cellular and humoral immune response indicators associated with disease status and (5) to identify risk factors for CL. Fourteen percent of subjects had parasitologically confirmed CL; 33% had evidence of prior disease. However, 17.2% of subjects with a negative CL clinical history presented with a positive Montenegro skin test (MST), indicating the possibility of subclinical infection. The species isolated from subject lesions were L. guyanensis (63%), L. panamensis (33%), and L. brazilensis (4%). Mean specific anti-Leishmania IgG and IgM OD serum levels were highest in subjects diagnosed with current CL, followed by those with prior CL, and were lowest in healthy subjects, respectively (0.56 +/- 0.27 vs 0.33 +/- 0.2 vs 0.22 +/- 0.14; F-ratio = 74; P < 0.00001) and (665 +/- 270 vs 481 +/- 220 vs 301 +/- 128.5; F-ratio = 37; P < 0.00001). Likewise, subjects with present CL had measurably higher MST reactions (13 +/- 6.7 mm) than those with prior CL (10.9 +/- 7.8 mm) or healthy individuals (2.4 +/- 2.5 mm; F-ratio = 106; P < 0.00001). Serum concentrations of IgG were predicted by lesion number (t = 2.5; P = 0.018), size (t = 3.7; P = 0.0006), and duration (t = 3.5; P = 0.0013). Furthermore, the MST induration size increased as a function of lesion number (t = 3.0; P = 0.005) and size (t = 3.4; P = 0.022). Subject age and sex did not predict serum IgG or IgM concentrations or MST reactions in the 3 disease groups. Although no sex differences were found with respect to clinical characteristics, children < or = 12 years of age were almost 3 times more likely to have CL lesions or scars located on the face and head area compared to adults (OR = 2.75; 95% CI = 1.4-5.6, P = 0.004). The risk factors associated with disease included age under 5 years (AOR = 1.5; 95% CI = 0.48-2.35), male gender in adults (AOR = 2.8; 95% CI = 1.1-7.8), and wood and/or cane exterior house walls (AOR = 1.8; 95% CI = 1.4-2.5). In contrast, electric home lighting was associated with decreased risk (AOR = 0.7; 95% CI = 0.4-2.3). The results suggest that it may be possible to modify a portion of the risk of CL by making changes in the housing environment which may help to reduce the amount of human-vector contact.

Adolescent↗
PubMed1997

Autocrine/paracrine regulation of normal human corpus luteum development.

The human corpus luteum (CL) is a transient endocrine gland regulated primarily by the age-dependent action of LH/hCG, which initiates a series of cell-specific processes necessary for the structure and also function of the gland. An extensive local regulation of the luteal function also exists, based on the heterogeneity of the cellular composition of the CL. It is most likely that interactions occur among the different subpopulations of steroidogenic (large and small luteal cells) and nonsteroidogenic cells (leukocytes, endothelial cells, and fibroblasts). Therefore, local produced substances, including steroids, growth factors, reactive oxygen species, and, recently, nitric oxide, may modulate luteal life span. The knowledge of the basic events involved in the control of human luteal function may lead to a better understanding of the physiopathology of the human menstrual cycle.

Corpus Luteum↗
PubMed1997

Regulatory role of angiotensin II on progesterone production by cultured human granulosa cells. Expression of angiotensin II type-2 receptor.

The role of angiotensin II (AngII) in ovarian steroidogenesis is not clearly understood. In order to study its action on progesterone synthesis and to determine which receptor subtype is involve, granulosa cells obtained from women undergoing in-vitro fertilization were cultured for 2 or 4 days and then incubated in the presence of AngII (10(-7) M) with or without human chorionic gonadotrophin (HCG, 10 IU/ml) for 3 or 18 h. In cells cultured for 2 days, incubation with AngII decreased progesterone secretion by 36%, and inhibited activity of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) by 87% (P < 0.05), although its expression was not significantly reduced. However, in cells cultured for 4 days, progesterone production was enhanced by incubation with AngII (38%), and no change was observed in 3 beta-HSD expression. Both inhibitory and stimulatory effects were dose-dependent. Progesterone secretion was increased (93%) by incubation with HCG of cells cultured for 4, but not for 2 days, and no potentiation was observed with AngII. Treatment with PD123177 completely blocked the action of AngII and decreased the HCG-stimulated secretion of progesterone by 27%. Angiotensin type-2 (AT2) receptor mRNA was expressed in cells cultured for 4 days. In conclusion, AngII showed a regulatory role in in-vitro progesterone production by human granulosa luteinized cells, modulating the activity of 3 beta-HSD. It is likely that these actions may be mediated via membrane receptors, possibly of the AT2 receptor family.

Angiotensin II↗
PubMed1997

[Results of salvage treatment of carcinoma of the larynx recurring after radiotherapy].

An analysis is made of salvage treatments and their results after unsuccessful radiotherapy in 113 carcinomas of the larynx. A group of 27 patients (24%) was excluded from salvage treatment. In the remaining 86 patients (76%), radical surgical salvage treatment was tried: total laryngectomy (74 cases) or partial surgery (12 cases). Four of the 12 patients treated with partial surgery suffered a second local relapse, which was rescued by new surgery. Treatment was successful in 72% of the laryngectomized patients and in all those treated with partial surgery. Survival correlated with local (T) and regional (N) extension of the initial tumor, its location, and simultaneous regional relapse. In contrast, survival did not correlate with the time interval between end of radiotherapy and relapse, or with local tumoral extension in the resection piece in surgically treated cases (rpT).

Carcinoma↗
PubMed1996

Differential steroidogenic response of human luteal cell subpopulations.

The differential capacity for steroid synthesis of human luteal cell subpopulations was investigated in a well defined cell culture system. Corpora lutea were enzymatically dissociated, and the two cell types were obtained by a discontinuous Percoll gradient. Both cell types were cultured for 24 h with dibutyryl cAMP (1 mM), oestradiol (2.5 microM) and testosterone (1 microM). Steroid production was measured in the culture media and aromatase activity for both cell type subpopulations was also determined. Basal production of progesterone, oestradiol and testosterone was significantly greater in large cells than that in small cells (P < 0.05). Nevertheless, a greater response of small cells to several in-vitro treatments was observed. Thus, synthesis of progesterone, oestradiol and testosterone was significantly stimulated in these cells (P < 0.05) by dibutyryl cAMP. Interestingly, a 3.3-fold increase of progesterone production was also observed in the large luteal cell subpopulation. When oestradiol was added to the culture media, a 36% decrease of progesterone production (P < 0.05) by small cells was obtained, while progesterone synthesis by large cells was not significantly affected. Testosterone treatment of cells enhanced oestradiol production by both cell subtypes (P < 0.05), although the stimulatory action was greater in the small cell cultures (5.9-fold). These data indicate that the steroidogenic activity of the small cell subpopulation is highly dependent on endocrine and paracrine stimulatory mechanisms, while large cells possess a greater intrinsic steroidogenic capacity.

Adult↗
PubMed1995

[Malignant pleural mesothelioma: clinical characteristics, prognostic factors and treatment].

Malignant pleural mesothelioma soon leads to death no matter what type of treatment is provided. We discuss the clinical signs, prognostic factors and treatment given in 41 cases managed over the past 13 years in our oncology department. 32% had been exposed to asbestos, 61% were 60 years old or younger, 71% had a Karnofsky's index > or = 80% and 63% were stage I (Butchart). The first symptom leading to diagnosis was pain in 66% and mean time between first symptom and diagnosis was 3 months. Thirty patients never experienced full remission of disease: 15 were treated with palliative chemotherapy (CHT), 1 with palliative radiotherapy (RT), 5 with partial pleurectomy (PP) plus RT and/or CHT. Nine were given symptomatic treatment only. Only 11 (27%) patients experienced full remission after treatment: 7 had had extrapleural pneumonectomy, 2 had been given CHT and RT series and 4 had undergone PP with or without RT and/or CHT follow-up. Only 3 of these patients were still alive with no relapse more than 1 year later. Mean survival was 8 months. Univariate analysis revealed that the prognostic factors influencing survival were age and Karnofsky's index. Patients initially treated with surgery had a higher rate of survival. In conclusion, only Karnofsky's index and age were prognostic factors in our series. The better survival of patients initially treated surgically is probably related to prior screening.

Adolescent↗
PubMed1995

Randomized trial of neoadjuvant cisplatin and fluorouracil versus carboplatin and fluorouracil in patients with stage IV-M0 head and neck cancer.

PURPOSE: A randomized trial was designed to compare cisplatin (CDDP) and fluorouracil (FU) versus carboplatin (CBDCA) and FU as neoadjuvant treatment in stage IV-M0 head and neck cancer to assess whether CBDCA-FU is better than CDDP-FU with regard to response and toxicity. PATIENTS AND METHODS: Patients were randomized to receive CDDP 100 mg/m2 intravenously on day 1 and FU 5,000 mg/m2 over a 120-hour continuous infusion, or CBDCA 400 mg/m2 over a 24-hour continuous infusion on day 1 and FU with the same schedule. Both regimens were repeated every 21 days. The patients received three courses of chemotherapy, excluding those who failed to achieve a partial response (PR) after the second course. Complete responders were treated with radiotherapy. The remaining patients underwent surgery if the tumor was resectable. RESULTS: Interim analysis was performed when 95 patients were included. The trial was stopped due to significantly better results in the control arm. Differences in response (P = .04) were favorable to CDDP-FU. Hematologic toxicity predominated in the CBDCA-FU arm (P < .001). Mucositis and vomiting predominated in the CDDP-FU arm (P = .03, P < .001, respectively). Favorable outcomes (complete response [CR] plus any grade of toxicity and PR plus grade 0 to 3 toxicity) predominated in the CDDP-FU arm (P = .02). Only the treatment assigned was associated with response (P = .02) and favorable outcomes (P = .009) in the logistic regression analysis. In the CDDP-FU arm, disease-free and overall survival were significantly better. Cox regression analysis showed that only treatment association with disease-free survival remains significant. CONCLUSION: Our results indicate that CDDP-FU is more effective than CBDCA-FU as neoadjuvant treatment in stage IV-M0 head and neck cancer.

Adult↗
PubMed1995

Multihormonal regulation of progesterone synthesis in cultured human midluteal cells.

The objectives of this investigation were to examine in vivo insulin like-growth factor-I (IGF-I) secretion by the human midcorpora lutea (mid-CL) and the effects of IGF-I, hCG, FSH, and human GH on progesterone (P) production by CL cells obtained from patients at laparotomy. We first examined whether the CL produces IGF-I by measuring IGF-I levels in the ovarian vein from the ovary bearing the CL. The IGF-I concentration in the ovarian vein bearing the CL (206 +/- 31 ng/mL) was significantly increased compared to the concentration in the contralateral ovarian vein (179.2 +/- 32 ng/mL; P < 0.05). Luteal cells isolated from mid-CL were cultured in serum-free medium 199 in the presence and absence of hCG, FSH, GH, and graded concentrations of IGF-I. At the end of the incubation period (24 h), P levels in the medium were measured by RIA. The treatment with IGF-I (0.1-10 ng/mL) showed a dose-dependent stimulatory action of IGF-I on P synthesis in the luteal cell system, being maximal between 5-10 ng/mL. The treatment with hCG (10 IU/mL), IGF-I (5 ng/mL), and GH (1000 ng/mL) increased basal P synthesis by 300%, 80%, and 30%, respectively (P < 0.001 and P < 0.05). FSH (100 ng/mL), either alone or in combination with IGF-I, failed to stimulate P synthesis. Treatment with IGF-I monoclonal antibody (1:5000) completely reduced P synthesis induced by 5 ng/mL IGF-I and slightly reduced basal P synthesis as well as GH-stimulated P synthesis by human midluteal cells. To further evaluate the specific role of IGF-I on luteal steroidogenesis, IGF-I receptor was identified by chemical cross-linking of [125I]IGF-I to mid-CL membranes. Experiments conducted in the absence and presence of unlabeled IGF-I (500 ng) revealed proteins with characteristics of the type I IGF receptor. These results are consistent with multihormonal regulation of P synthesis by the human mid-CL. hCG and IGF-I play a major role in the stimulation of P synthesis and, to a lesser extent, human GH. These in vivo and in vitro data suggest that the CL is a site of secretion, action, and reception of IGF-I during the midluteal phase.

Adult↗
PubMed1995

Function preservation in stage III squamous laryngeal carcinoma: results with an induction chemotherapy protocol.

Until recently, standard treatment for stage III laryngeal carcinoma (LC) was total laryngectomy and radiotherapy. Recent data suggest that induction chemotherapy (ICH) plays a role in preserving function in advanced head and neck cancer. No reports to date prospectively evaluate ICH exclusively in stage III LC. The authors designed a sequential phase II trial to assess if ICH allowed a conservative treatment in this disease. The objective of the first part of the study was to rule out a complete response rate with ICH below 30% with P < .05. ICH protocol consisted of three courses of cisplatin 100 mg/M2 on day 1 and 5-fluorouracil 5000 mg/M2 continuous infusion over 120 hours. Radiotherapy was administered to patients who attained a complete response (CR). Functional surgery (FS) was planned for patients with partial response. A total laryngectomy followed by radiotherapy was performed when FS was not feasible. Fifty-two previously untreated patients (all males) with squamous stage III LC were diagnosed in our institution, and 46 were entered in the ICH trial. After 9 patients were included, data showed 7 (78%) CR, ruling out a CR rate of less than 30%. After ICH, a CR was achieved in 29 (63%) of 46 patients. At the end of treatment, 35 patients (76%) had a functioning larynx. With a median follow-up of 3 years, larynx function was preserved in 26 (57%) of 46 patients and in 64% of survivors. Four-year actuarial larynx function preservation, overall survival, and disease-free survival were 55%, 77%, and 67%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Functional luteolysis in response to hydrogen peroxide in human luteal cells.

To evaluate the effect of reactive oxygen species in human corpus luteum function, we investigated whether hydrogen peroxide (H2O2) affects the in vitro luteal cell production of steroids. H2O2 treatment (1.0-100 microM) of mid and late luteal cell cultures elicited a dose-dependent decrease in basal progesterone production. However, treatment of mid luteal cells with a low concentration of H2O2 (0.01 microM) significantly stimulated progesterone secretion (P < 0.05). In addition, H2O2 (100 microM) markedly inhibited human chorionic gonadotropin (hCG)-stimulated progesterone and estradiol secretion. cAMP production was enhanced (2.4-fold, P < 0.05) by hCG treatment of luteal cells. The addition of H2O2 (0.1-100 microM) to hCG-stimulated luteal cell cultures elicited a decrease in cAMP concentration (P < 0.05) and in the specific binding of radiolabeled hCG by luteal cells. Progesterone and estradiol production stimulated by dibutyryl cAMP were significantly inhibited by H2O2 (P < 0.05). These findings suggest that H2O2 interferes with basal steroid production and, in hCG-stimulated conditions, it may inactivate the gonadotropin-receptor complex. The anti-steroidogenic action of H2O2 therefore raises the possibility of a modulatory role of H2O2 in human luteal steroidogenesis.

Adult↗
PubMed1995

[Evaluation of bone mass in hip fractures measuring lumbar spine and contralateral hip with bone densitometry].

Hip fracture is frequent in postmenopausal women with osteoporosis. The aim of this work was to assess bone mass in women with hip fracture and compare it with that of normal women. Bone densities of lumbar spine (considering areas with and without spondylosis), femoral neck, greater trochanter, and unfractured hip Ward's triangle were measured with a double beam isotopic densitometer. Thirty-one women aged 58-95 years old were studied and compared with normal women studied at the same laboratory. Bone densities in fractured and normal women were 0.82 +/- 0.16 and 0.85 +/- 0.05 g/cm2 in lumbar spine respectively (NS), 0.74 +/- 0.15 and 0.85 +/- 0.05 g/cm2 in lumbar spine without spondylosis respectively (p < 0.001), 0.60 +/- 0.11 and 0.65 +/- 0.08 g/cm2 in femoral neck respectively (NS), 0.49 +/- 0.09 and 0.57 +/- 0.05 g/cm2 in greater trochanter respectively (p < 0.001) and 0.48 +/- 0.12 and 0.52 +/- 0.09 g/cm2 in Ward's triangle respectively (NS). It is concluded that the larger differences in bone density between women with and without hip fracture are observed in the greater trochanter.

Absorptiometry, Photon↗