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Biomedical subjects

B Ortega

Publications and source records attributed to B Ortega.

13 recordsLinked to original sources
PubMed1999

Splicing of a retained intron within ROMK K+ channel RNA generates a novel set of isoforms in rat kidney.

The renal outer medulla K+ channel (ROMK) family of K+ channels may constitute a major pathway for K+ secretion in the distal nephron. To date, four main isoforms of this gene have been identified in the rat that differ only in their NH2-terminal amino acids and that share a common "core exon" that determines the remaining protein sequence. Using RT-PCR, we have identified a new set of ROMK isoforms in rat kidney that are generated by the deletion of a region within the ROMK core sequence that is identifiable as a typical mammalian intron. This splicing event was shown to be reproducible in vitro by detection of deleted ROMK mRNA in Madin-Darby canine kidney (MDCK) cells stably transfected with the gene for ROMK2. Translation of the deletion variant of ROMK2 was confirmed in vitro and visualized in MDCK cells following transient transfection with an enhanced green fluorescent protein tag. The deletion in this core region is predicted to generate hydrophilic proteins that are approximately one-third of the size of native ROMK and lack membrane-spanning domains.

Amino Acid Sequence↗
PubMed1998

Corticosteroids and radiation mucositis in head and neck cancer. A double-blind placebo-controlled randomized trial.

Patients with head and neck cancer were randomized in a double-blind manner to receive 40 mg/day prednisone (n = 32) or placebo (n = 34). The prescribed daily tumour dose was 1.6 Gy twice daily with an interfraction interval of > or =6 h. Treatment interruptions were at the discretion of the radiation oncologists. The primary study end-point was the total duration of treatment. A mean 4.4 day reduction was observed in the total elapsed treatment duration for the prednisone arm, 34.3 versus 29.9 days (P = 0.013), which paralleled a significantly lower median total tumour and biologically effective dose (BED) Gy10 in this arm. A trend favouring shorter treatment interruptions in the prednisone arm was also found, but not a reduction in the intensity or duration of mucositis.

Adult↗
PubMed1997

Induction chemotherapy and radiotherapy of advanced cancer of the cervix: a pilot study and phase III randomized trial.

PURPOSE: This study assessed the effectiveness and toxicity of induction chemotherapy (CT) and radiation therapy (RT) in the treatment of locally advanced carcinoma of the cervix with data provided by a pilot study and a randomized trial. METHODS AND MATERIALS: Eighty-six patients with International Federation of Gynecology and Obstetrics (FIGO) Stage IB-IVA (Stage IB >4-cm tumor diameter) (Group A) were entered in a pilot study and treated with cisplatin (50 mg/m2), vincristine (1 mg/m2 on days 1, 11, and 21), bleomycin (25 mg/m2 infusion on days 1-3, 11-13, and 21-23), and standard RT. Ninety-six patients were randomized to either this same CT regimen and RT, or RT alone (Group B: CT plus RT or RT). RESULTS: In Group A, 58% responded to induction CT. With a mean follow-up of 78 months, 73% achieved pelvic control (LRC), and 55% were disease-free survivors. Response to CT was not a marker for ultimate LRC or increased disease-free survival (DFS). In Group B, 62% responded to CT. With a mean follow-up of 43 months, LRC was 68% and 65% for all randomized patients in the CT plus RT and RT arms, respectively (p = NS). In patients who completed treatment, 78% and 70%, respectively, achieved LRC (p = NS). Disease-free survival rates were 38% and 49% for randomized patients in the CT plus RT and RT arms (p = NS), respectively, and 44% and 52% in those patients completing treatment (p = NS), respectively. Complications were acceptable. CONCLUSION: Data from this study did not prove the efficacy of induction CT before definitive RT in locally advanced cancer of the cervix. Induction CT with the currently used combinations and modes of administration should not be considered standard therapy.

Adult↗
PubMed1995

Breast conservation treatment of early stage breast cancer: patterns of failure.

PURPOSE: This study retrospectively assesses the patterns of failure in conservatively treated early stage breast cancer patients by correlating various clinical, pathologic, and treated-related factors with local, axillary, and distant relapse. METHODS AND MATERIALS: Between 1973 and 1990, 796 patients (817 breasts) received breast conservation surgery followed by radiotherapy. Local recurrences were counted as events even if they occurred simultaneously or after the appearance of axillary or distant metastases. RESULTS: The 10-year actuarial relative disease-free survival (DFS) rate for T1N0, T2N0, and T1-2N1 was 82%, 71%, and 54%, respectively. Stage N0 patients had a significant DFS advantage over N1 patients (p = 0.02). The 15-year actuarial local recurrence-free rate for T1 and T2 tumors was 82% and 87%, respectively (p = nonsignificant). Univariate analysis identified three significant risk factors for local relapse: (a) 48 breasts with tumors showing an extensive intraductal component had a crude local recurrence rate of 23% compared to 8% for 769 breasts without intraductal component (p = 0.0016); (b) the actuarial 10-year local recurrence-free rate for patients under age 40 years was 64% compared to 88% for patients over 40 years (p < 0.0001); (c) the 10-year actuarial local recurrence-free rate for 416 postmenopausal women without adjuvant tamoxifen was 83% compared to 97% for 107 postmenopausal women with tamoxifen (p = 0.0479). Salvage therapy for operable local recurrent patients resulted in a 8-year actuarial DFS rate of 47%, significantly lower than that obtained with primary treatment. The incidence of axillary relapse as the first sign of recurrence was 2%, and could be correlated with the lack of axillary dissection (p < 0.0000005) and primary tumor size (p = 0.03). Radiotherapy to the axilla did not influence axillary relapse. Actuarial 5-year DFS rate after treatment of isolated axillary recurrence was 27%. Axillary failure was a marker for distant failure. Contralateral breast cancer occurred in 8% of patients and did not have a detrimental effect on survival. Adjuvant tamoxifen decreased the 9-year actuarial incidence of contralateral breast cancer from 10% to 4% (p = 0.053). CONCLUSIONS: Tumors with extensive intraductal component, age under 40 years, and the omission of adjuvant tamoxifen in postmenopausal women increased local recurrence rate. Stage T2 and the lack of axillary dissection increased axillary recurrence rate. Stage N+ and local or axillary relapse increased distant failure rate. Axillary irradiation did not influence locoregional control nor survival. Improved therapy is needed for relapsing patients.

Actuarial Analysis↗
PubMed1995

Long-term survival in a surgically treated non-encapsulated mediastinal primary liposarcoma. Diagnostic utility of core-needle biopsy for mediastinal tumors.

Primary liposarcomas of the mediastinum are uncommon tumors. Only six cases of mediastinal liposarcomas with survival after surgery longer than five years have been reported and only one of these was a non-encapsulated tumor. We report a new case of non-encapsulated primary liposarcoma of the mediastinum with long-term survival. The diagnosis was carried out using a CT-guided core-needle biopsy. We emphasize the utility of this technique to diagnose this kind of mediastinal tumors. A non-encapsulated primary liposarcoma of the mediastinum surgically treated with long-term survival is reported. We emphasize the diagnostic utility of CT-guided core-needle biopsy for the tumors.

Biopsy, Needle↗
PubMed1994

[Variations of angiotensin converting enzyme in chronic obstructive pulmonary disease and chronic respiratory insufficiency].

UNLABELLED: Maintained hypoxia has been reported to induce inactivation of the Angiotensin Converting Enzyme (ACE). Variations have also been observed in patients with chronic obstructive pulmonary disease (COPD) who have chronic hypoxemia and loss of the vascular endothelium. OBJECTIVES: 1) to determine serum ACE activity in patients with COPD treated with and without continuous ambulatory oxygen therapy (CAOT); 2) to verify whether there is a correlation between ACE and any hematological, spirometric or gasometric parameter. METHODS: fifty-eight patients fulfilling clinical and spirometric parameters of COPD were studied. Patients were assigned to two groups of therapy: A) Group A, without Continuous Ambulatory Oxygen Therapy (CAOT): 31 males and 1 female (mean age: 64.8 +/- 6.52). B) Group B (with CAOT): 23 males and 3 females (mean age years: 63.76 +/- 8 years). The following procedures were performed: spirometry, gasometry, blood chemistry, and serum ACE measurements by means of a radioenzymatic assay. The Student "t" test with the Bonferroni correction and Pearson regression analysis were used for the statistical analysis. RESULTS: significant differences were observed for ACE values between Group A and Group B: 42.81 +/- 11.30 vs. 33.40 +/- 9.43 mumol/min/l, with a p value of 0.001, and also between Group B and reference values: 33.40 +/- 9.43 vs. 39.70 +/- 9.65 mumol/min/l, with a p value of 0.002. No differences were observed between Group A and reference values. No correlations wer found between ACE and any of the variables studied. CONCLUSIONS: ACE was not decreased in all patients with COPD. ACE was decreased only in patients with COPD and respiratory insufficiency requiring CAOT and with advanced disease. This results can be correlated with changes in vascular endothelium, pulmonary parenchyma and metabolism. It could be a marker of poor prognosis or advanced disease.

Aged↗
PubMed1993

[Elevated negative predictive value of angiotensin converting enzyme in the diagnosis of active sarcoidosis].

OBJECTIVE: To evaluate the usefulness of angiotensin converting enzyme (ACE) in the differential diagnosis of active sarcoidosis in action with other interstitial and granulomatous processes. METHODS: The study involved 30 patients with a histological diagnosis of sarcoidosis, 38 subjects with anatomopathologically and/or microbiologically confirmed pleuropulmonary tuberculosis, and 12 subjects with idiopathic pulmonary fibrosis confirmed by histological studies. Following the technique developed by Rohatgi and Ryan, a radioenzymatic system was used to determine the activity of serum ACE. In patients with sarcoidosis, levels of ACE were measured in active cases as well as those in remission. Our laboratory reference values for those over 20 years of age are 39.84 +/- 9.19 mumol/min/l. RESULTS: Levels of ACE were significantly higher (p < 0.001) in active sarcoidosis (67.71 +/- 17.73 mumol/min/l) than during inactivity (41.18 +/- 16.00 mumol/min/l), tuberculosis (46.99 +/- 13.65 mumol/min/l), or fibrosis (35.87 +/- 11.36 mumol/mol/l). A cut-off point of 59 mumol/min/l shows a significant association with the diagnosis of active sarcoidosis (p < 0.001) and reaches a negative predictive value of 90.90%. CONCLUSION: The usefulness of serum ACE in the differential diagnosis of sarcoidosis should be reconsidered.

Adult↗
PubMed1992

[Can a prostatic adenocarcinoma simulate an acute myocardial infarction?].

The assay for the MB isoenzyme of creatine kinase is widely used in the diagnosis of acute myocardial infarction. Patients with metastatic carcinoma of the prostate may have an elevated serum creatine kinase BB fraction, which by immunoinhibition method may be read mistakenly as creatine kinase MB. We report the case of a patient with a history of myocardial injury, chest pain, total CK above of reference range and CK-MB isoenzyme, determinated with an immunoinhibition technique, larger than 100% of enzymatic activity of total CK, that was carrier of a prostatic adenocarcinoma in stage D2. We comment the diseases in which the CK-BB fraction may be elevated, discuss the laboratory methods for the determination of creatine kinase isoenzymes, and revised, briefly, the properties of the new immunoassays, that measure mass concentration of creatine kinase MB, in the diagnosis of acute myocardial infarction.

Adenocarcinoma↗
PubMed1987

Elective neck irradiation in the treatment of cancer of the oral tongue.

A total of 69 patients with squamous cell carcinoma of the oral tongue Stages T1-2-3 N0 were treated between 1952 and 1982 at one cancer center in Montevideo, Uruguay. Of 52 patients with the primary disease controlled, 2 had elective cervical lymph node dissection, and were therefore excluded from the study, 25 were treated with elective neck irradiation, and 25 were followed without irradiation to the neck. In the untreated group, 40% developed neck node metastases, while this was observed only in 20% of the group receiving elective neck irradiation, but only 4% recurred in the elective irradiated areas of the neck (p: 0.0028). The survival was the same for each group (5-year absolute survival with NED 67% for the neck irradiation group and 64% for the unirradiated group). From this retrospective study, we conclude that elective neck irradiation in carcinoma of the oral tongue decreases the incidence of neck metastases but an improvement in survival of these patients was not demonstrated.

Carcinoma, Squamous Cell↗
PubMed1986

The place of brachytherapy in the treatment of carcinoma of the tonsil with lingual extension.

One hundred forty-four of 170 patients (85%) were seen with cancer of the tonsil and received radical irradiation between 1959 and 1980. A 39% crude 3-year disease-free survival rate and a 51% locoregional control rate were observed. Locoregional relapse related to T Stage was 6, 43, 58, and 64% for T1, T2, T3, and T4, respectively. Fifty-four of 144 patients (37%) showed tongue extension, 20% in T1-T2 stages and 50% in T3-T4 stages. Local relapse was 64% and the 3-year disease-free survival rate was 23% in 39 patients with tongue extension treated with external irradiation alone, versus 33 and 43% respectively for 90 patients with no tongue extension. The increase of lymph node metastases or neck recurrences was not related to tongue extension. In 15 patients with tongue extension, treated with external radiation plus brachytherapy, the local relapse was 40% and the 3-year survival rate 60%. External irradiation plus brachytherapy was significantly related to lower local relapse and increased survival rate compared to external irradiation alone in cancer of the tonsil with tongue extension. The combined modality was not associated with increased risk of radiation complications.

Brachytherapy↗