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Biomedical subjects

Juan Ybarra

Publications and source records attributed to Juan Ybarra.

8 recordsLinked to original sources
PubMed2006

Role of pre-operative imaging using 99mTc-MIBI and neck ultrasound in patients with secondary hyperparathyroidism who are candidates for subtotal parathyroidectomy.

PURPOSE: The purpose of this study was to assess whether pre-operative (99m)Tc-methoxyisobutylisonitrile (MIBI) scintigraphy and neck ultrasound (US) are of value in improving the outcome of subtotal parathyroidectomy in patients with secondary hyperparathyroidism. METHODS: Forty-eight consecutive haemodialysis patients with severe secondary hyperparathyroidism prospectively underwent "blinded" subtotal parathyroid surgery, with 1-year follow-up to establish cure or relapse of their secondary hyperparathyroidism. Double-phase (99m)Tc-MIBI scintigraphy and neck US were performed pre-operatively in all patients. When the preserved gland showed (99m)Tc-MIBI uptake or an abnormal size on US, it was considered that "(99m)Tc-MIBI advice" and "US advice", respectively, had not been followed. Pre-operative and follow-up parathyroid hormone (PTH) levels were obtained in all patients. All data were evaluated on a patient by patient basis. RESULTS: Four parathyroid glands were identified in each patient at primary surgery, resulting in an operative success rate of 100%. Their weight ranged from 15 to 7,300 mg (mean 1,120+/-900 mg). Nine of the 48 patients (19%) showed a recurrence of their secondary hyperparathyroidism. The recurrence rate was 2% (1/48) and 10% (5/48), respectively, when (99m)Tc-MIBI and US advice was followed. The sensitivity, specificity, NPV and PPV for pre-operative imaging were 72%, 95%, 97% and 80% respectively for (99m)Tc-MIBI, and 55%, 67%, 87% and 28% for US. CONCLUSION: (99m)Tc-MIBI scintigraphy is a reliable non-invasive exploratory tool and its preoperative use results in a significant reduction in the number of recurrences in haemodialysis patients with secondary hyperparathyroidism who are candidates for subtotal parathyroidectomy. The use of neck US did not significantly improve the results obtained with (99m)Tc-MIBI alone.

Adult↗
PubMed2006

PTEN promoter methylation in sporadic thyroid carcinomas.

The tumor-suppressor gene PTEN/MMAC1, on chromosome 10q23.3, has been implicated in an important number of human tumors, such as thyroid carcinomas. PTEN somatic mutations occur in sporadic tumors of the endometrium, brain, prostate, or melanomas, while germline mutations predispose to development of the multiple hamartoma syndromes (i.e., Cowden's disease and Bannayan-Zonana syndrome). Activation of the two alleles of PTEN is required for its tumor-suppression role. Because the frequency of PTEN suppression in thyroid tumors exceeds that of PTEN mutations or deletions, it is very likely that epigenetic mechanisms, such as promoter hypermethylation, may account for its inactivation in a subset of tumors. The main aim of this study was to assess the frequency of promoter hypermethylation of PTEN in thyroid tumors. We studied frozen tissue samples from 46 papillary carcinomas, 7 follicular carcinomas, 6 follicular adenomas as well as 39 normal thyroid tissue samples. Methylation-specific polymerase-chain reaction (PCR) with three different sets of primers was used. Two of the primer sets were designed to avoid any interference with PTEN pseudogene promoter. PTEN promoter hypermethylation was detected in 21 of 46 (45.7%) papillary carcinomas, 6 of 7 follicular carcinomas, and 5 of 6 follicular adenomas. It was negative in all normal tissues. Negative immunohistochemical staining for PTEN was significantly associated with the presence of promoter hypermethylation (p < 0.001). These results show a high frequency of PTEN promoter hypermethylation, especially in follicular tumors, suggesting its possible role in thyroid tumorigenesis.

Adenoma↗
PubMed2005

A new educational program for patients suffering from sleep apnea syndrome.

OBJECTIVE: Patients' knowledge and beliefs about their chronic illnesses such as OSAS are known to influence a range of health related variables, including treatment compliance. It is for that reason that this interdisciplinary program centred on the therapeutic education of the patients was conceived by two medical teams with the aim of creating a new coverage of the patients affected of OSAS. METHODS: Thirty-five OSAS patients were consecutively collected among those regularly followed at the Service of pneumology outpatient facility. The psycho-educational methodology as well as the courses are described in detail. Patients were admitted for 36 h at the Service of Therapeutic Education for Chronic Diseases for both individual and group multidisciplinary approach to their disease. Groups of 3-4 patients discuss benefits, inconvenience as well as CPAP representations and manipulation of the device in small workshops. RESULTS: The therapeutic objectives, the educational methods, the program evaluation are presented. Preliminary results show a clinical improvement of the duration of CPAP use (0.7 +/- 0.2 h/night). 24% of patients increased the CPAP use more than one hour per night 3 months later. The Epworth sleepiness scale is significantly improved 3 months later (p < 0.05). CONCLUSION: We describe a new therapeutic educational interdisciplinary program for patients affected by OSAS. Its efficacy will be tested prospectively in a larger group and in the long term. PRACTICE IMPLICATIONS: The educational methods were applicable to the patients affected of OSAS bringing new specific strategies to improve the CPAP use. Patients had a positive attitude towards the CPAP treatment.

Continuous Positive Airway Pressure↗
PubMed2005

Unchanged hypovitaminosis D and secondary hyperparathyroidism in morbid obesity after bariatric surgery.

BACKGROUND: Morbidly obese patients have been reported to present with vitamin D insufficiency and secondary hyperparathyroidism. We assessed whether bariatric surgery alters the 25-hydroxyvitamin D (calcidiol) and intact parathyroid hormone (iPTH) levels in patients presenting with morbid obesity. METHODS: A cross-sectional survey was conducted on 144 patients of whom 80 had not undergone bariatric surgery, while 64 had bariatric surgery at a mean of 36 months previously. Calcidiol levels were defined as being normal (>50 nmol/L), insufficient (2550 nmol/L) and deficient (<25 nmol/L). Mild secondary hyperparathyroidism was defined as iPTH >7.3 pmol/L with simultaneous normal values for creatinine, calcium and phosphorus. RESULTS: 80% of the patients presented low vitamin D levels and mild secondary hyperparathyroidism. Previous surgery or the presence of diabetes did not influence calcidiol levels. Corrected serum calcium, phosphorus, alkaline phosphatase, iPTH and Calcidiol were similar between subjects with and without surgery. CONCLUSIONS: Vitamin D deficient states with secondary hyperparathyroidism in the morbidly obese precede and are not significantly affected by bariatric surgery. Hypovitaminosis D with secondary hyperparathyroidism due to low calcidiol bio-availability should be added to the crowded list of sequelae of morbid obesity. While further studies are warranted, it seems advisable to support vitamin D supplementation in the morbidly obese population.

Adult↗
PubMed2004

Evaluation of nutritional education using concept mapping.

UNLABELLED: The concept mapping method is presented in the current study as a new tool to assess the learning process taking part in the hallmark of a nutritional education program addressed to obese diabetic patients. POPULATION: eight patients were interviewed prior to and after completion of 1-week in-hospital stay during which concept maps were designed. Concept maps quantitative and qualitative analysis disclose both (i) the importance of previous knowledge among patients prior to nutritional education and (ii) the maintenance of misconceptions after it. Nutritional education allows patients to acquire and structure their knowledge while providing them with a certain amount of medical vocabulary. An underlying correlation between concept maps design and the results of psychological tests identifying eating behaviour troubles (EBT), depression or anxiety has not been clearly identified. However, the nutritional education is more beneficial to those patients with a higher degree of self-assertiveness and with a lesser degree of anxiety, depression and eating disorder.

Attitude to Health↗
PubMed2004

Predicting the effect of intravenous calcitriol on parathyroid gland activity using double-phase technetium Tc 99m-sestamibi scintigraphy.

BACKGROUND: Although intravenous calcitriol is useful for decreasing intact parathyroid hormone (iPTH) blood levels in patients with secondary hyperparathyroidism (SHP) undergoing hemodialysis, approximately half these patients remain refractory to this treatment. The current study measures the diagnostic utility of double-phase technetium Tc 99m-sestamibi (MIBI) scintigraphy in predicting the response to calcitriol treatment. METHODS: Sixty hemodialysis patients with SHP with iPTH blood levels between 240 and 600 pg/mL (ng/L) were selected. Initial intravenous calcitriol pulse therapy was 6 microg/wk (for iPTH levels of 400 to 600 pg/mL [ng/L]) or 3 microg/wk (for iPTH levels of 240 to 400 pg/mL [ng/L]). MIBI scintigraphy was performed before the onset of calcitriol therapy and repeated 1 year later. Patients were injected intravenously with 740 MBq of MIBI. Images were obtained at 15 minutes (thyroid phase) and 2 hours (parathyroid phase) after radiotracer administration. Focal areas of increased MIBI uptake were considered pathological parathyroid glands. RESULTS: Forty-eight patients completed the study. After 1 year, iPTH levels had decreased significantly in 95.2% (47 patients), whereas good control (iPTH < 240 pg/mL [ng/L]) was reached in 70.8% (34 patients) and only 4 patients had iPTH levels greater than 400 pg/mL (ng/L; all were patients with 3 MIBI-positive areas at baseline determination). At baseline, there were 30 patients (62.5%) with MIBI positive areas (1, 2, or 3 areas), which decreased to 14 patients (29%) at the end of the study period. No patient showed 4 positive areas at any time. The 18 patients (37.5%) with no MIBI-positive area at baseline remained unchanged. CONCLUSION: MIBI scintigraphy is a reliable exploratory tool in predicting the response to treatment with intravenous calcitriol in hemodialysis patients with SHP.

Adult↗
PubMedDate not supplied

Effects of bariatric surgery on vitamin D status and secondary hyperparathyroidism: a prospective study.

BACKGROUND: Morbidly obese patients have been reported to present with vitamin D insufficiency and secondary hyperparathyroidism. Scattered data are available regarding the effects of bariatric surgery on vitamin D status. We studied calcium metabolism and vitamin D status before and after bariatric surgery. METHODS: In this prospective study, 64 patients (M5/F59) fulfilled the inclusion criteria (i.e. 2 calcidiol serum determinations in the winter season) among 457 morbidly obese individuals who underwent Roux-en-Y gastric bypass (RYGBP) a mean of 36 months previously. Laboratory data (serum calcium, phosphorus, creatinine, alkaline phosphatase, albumin, calcidiol, albumin and iPTH) were determined before and after RYGBP. Pre- and postoperative calcidiol levels were categorized as being normal (>50 nmol/L), insufficient (25-50 nmol/L), and deficient (<25 nmol/L). Pre- and postoperative mild secondary hyperparathyroidism was defined as iPTH >7.3 pmol/L with simultaneous normal values for creatinine, calcium and phosphorus. RESULTS: RYGBP produced a significant weight loss coupled with a simultaneous increase in calcidiol (+28%, P<0.0005) and decrements in total alkaline phosphatase (-53%, P<0.0005) and iPTH (-74%, P=0.001). Corrected serum calcium, phosphorus, and creatinine levels were indistinguishable before and after RYGBP. Additionally, 37.5% of the patients maintained their calcidiol category, while 42.2 % improved it and 20.3% lost one category. CONCLUSIONS: RYGBP does not completely correct pre-existing vitamin D deficient states with secondary hyperparathyroidism. Low calcidiol bioavailability and or insufficient sunlight exposure do probably persist after bariatric surgery. While randomized controlled studies are warranted, it seems advisable to support vitamin D supplementation as well as increasing sunlight exposure in the morbidly obese population.

Adult↗