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Biomedical subjects

Marise Lazaretti-Castro

Publications and source records attributed to Marise Lazaretti-Castro.

9 recordsLinked to original sources
PubMed2006

[Evidences of physical agents action on bone metabolism and their potential clinical use].

The action of physical agents such as low level laser therapy, low-intensity pulsed ultrasound and electrical and electromagnetic fields on bone have been often studied, showing that they are able to promote osteogenesis, accelerate fracture consolidation and augment bone mass. The use of these therapeutic modalities was first based on the finding that bone is a piezoelectric material, that means it can generate polarization when deformed, transforming mechanical energy into electric energy, and this has widen therapeutic possibilities to bony tissue. The present work aims to present evidences of physiologic effects and mechanisms of action of these physical agents on bone metabolism, based on articles published in international scientific literature.

Bone Diseases↗
PubMed2006

[Parathyroid carcinoma].

Parathyroid carcinoma is a rare condition, comprising less than 1% of the cases of primary hyperparathyroidism (PHP). Nonetheless, due to its aggressiveness, and having prognosis dependent on the precocity of diagnosis and radical therapeutic approach, it is paramount that the clinical suspicion be made before surgery. Clinical presentation is typical of severe PHP, with a parathyroid tumor >1.5 cm, usually palpable. The pathologic features sometimes are difficult to characterize. Our experience with this condition (from 1983 to 2004) includes 7 cases, all symptomatic, hypercalcemic syndrome and bone disease present in most of them. In 6/7 the tumor was palpable, and in all the biochemical profile was compatible with severe PHP. Three patients died of complications of hypercalcemia. Recent findings point to a mutation on the gene HRPT2 as the molecular base for the development of this kind of tumor. The therapeutic approach is surgical and should include ipsilateral thyroidectomy and cervical exploration in order to find possible local metastasis. Post-surgical complications (mainly hypocalcemia) are proportional to the pre-existing metabolic alterations. The long-term prognosis depends upon the precocity of diagnosis, surgical success and control of hypercalcemia. New therapeutic approaches, based on bisphosphonates and calcimimetic drugs, as well as the possibility of genetic diagnosis, tend to ameliorate the prognosis of this severe affection.

Adult↗
PubMed2006

Hypoparathyroidism and pseudohypoparathyroidism.

The principal function of the parathyroid hormone (PTH) is maintenance of calcium plasmatic levels, withdrawing the calcium from bone tissue, reabsorbing it from the glomerular filtrate, and indirectly increasing its intestinal absorption by stimulating active vitamin D (calcitriol) production. Additionally, the PTH prompts an increase in urinary excretion of phosphorus and bicarbonate, seeking a larger quantity of free calcium available in circulation. Two mechanisms may alter its function, limiting its control on calcium: insufficient PTH production by the parathyroids (hypoparathyroidism), or a resistance against its action in target tissues (pseudohypoparathyroidism). In both cases, there are significantly reduced levels of plasmatic calcium associated with hyperphosphatemia. Clinical cases are characterized by nervous hyperexcitability, with paresthesia, cramps, tetany, hyperreflexia, convulsions, and tetanic crisis. Abnormalities such as cataracts and basal ganglia calcification are also typical of these diseases. Treatment consists of oral calcium supplementation associated with increased doses of vitamin D derivatives.

Calcitriol↗
PubMed2006

[Usefulness of intraoperative PTH measurement in primary and secondary hyperparathyroidism: experience with 109 patients].

INTRODUCTION: Intraoperative parathyroid hormone measurement (IO-PTH) was first described in 1988 and it's potentially useful in predicting cure after parathyroidectomy. The aim of this study was to evaluate IO-PTH decay profile and the utility of this procedure in predicting cure in primary (PHH) and secondary (SHH) hyperparathyroidism due to renal disease. PATIENTS AND METHODS: 109 patients were evaluated from 06/2000 to 12/2004. 33 had PHH and 76 SHH (52 in dialysis, 24 with renal graft). IO-PTH was measured at times 0 (before resection), 10, 20 minutes after parathyroidectomy using immunometric assay (Elecsys-PTH/Immunoassay-Roche). Time necessary to perform assay: 10 minutes. RESULTS: HPP patients: IO-PTH average decrease 79.2% from basal levels after 10 minutes. HPS: IO-PTH average decrease 85.8% and 87.6% after 10 minutes in dialysis and renal graft patients respectively. All patients were cured, except 2 (1 PHH, 1 SHH), because of a double adenoma and ectopic (mediastinal) parathyroid respectively. Failure in IO-PTH decrease was observed in both. CONCLUSION: IO-PTH measurement is useful in improving surgical success rates in PHH and SHH.

Adult↗
PubMed2005

Influence of ultraviolet radiation on the production of 25 hydroxyvitamin D in the elderly population in the city of São Paulo (23 degrees 34'S), Brazil.

The lack of vitamin D is a major changeable factor involved in the pathophysiology of osteoporosis. Since the major source for this hormone is its cutaneous synthesis via ultraviolet radiation (UVR), we studied the serum level of 25-hydroxyvitamin D (25OHD) in 250 free-living elderly people (79.1 years old) from a subtropical region according to the UVR incidence and its correlations with parathormone (PTH) and ionized calcium. UVR and 25OHD differed according to the season of the year (P<0.001), with greater radiation in the summer and less in the winter, whereas the 25OHD peak and nadir occurred in autumn and spring, respectively. The highest 25OHD mean was 67.2 nmol/l, and the lowest was 29.1 nmol/l corresponding, respectively, to the measure of the month subsequent to the one of most and least sunlight incidence. Clustered by season, the correlation between UVR and 25OHD for the following seasons was r=0.98 and between the PTH and 25OHD of corresponding seasons, r=-0.95. Vitamin D deficiency occurred in 15.4% of patients, insufficiency in 41.9% and secondary hyperparathyroidism in 55%. In conclusion, we found a seasonal variation in 25OHD levels that strongly correlated with the PTH levels when separated by the seasons of the year. The 25OHD levels correlated with the UVR of the previous quarter, requiring no less than 30 days for serum changes arising from exposure to or deprivation of UVR to be observed. The prevalence of vitamin D deficiency/insufficiency found was greater than expected, even when compared to countries exposed to less solar irradiation. Thus, measures to encourage greater sun exposure and food enrichment policies should also be considered.

Aged↗
PubMed2005

Bone mineral density and osteoporosis among a predominantly Caucasian elderly population in the city of São Paulo, Brazil.

This cross-sectional study covered 301 individuals over 70 years of age--207 women (W) and 94 men (M)--living in the city of São Paulo, Brazil. Our aims were to evaluate the prevalence of low bone mineral density (BMD) in this population and the possible factors that influence BMD. The subjects were submitted to a bone densitometry scan (DXA) to evaluate the BMD at lumbar spine (LS), femoral neck (FN), trochanter (T), total femur (TF) and total body composition. At the time, the participants filled in a questionnaire about lifestyle habits, diet and medical history, as well as having blood samples taken to check hormone and biochemical levels. Anthropometric parameters were measured. Osteopenia and osteoporosis were defined in accordance with the criteria suggested by the World Health Organization. In the different sites studied, the prevalence of osteopenia and osteoporosis varied, in men ranging 33.3-57.4% and 6.4-16.1%, respectively, and in women ranging 36.6-56.5% and 22.2-33.2%, respectively. Weight was the variable that most strongly correlated with BMD at the proximal femur in both sexes (men, r =0.44-0.52; women, r =0.48-0.52) and with BMD at LS in women (r =0.44). Height was the parameter that best correlated with BMD at LS in men (r =0.34). In men follicle-stimulating hormone, growth hormone and glycemia correlated with BMD at T and TF, while plasma albumin only correlated with BMD at T. In women glycemia correlated with BMD at LS, and follicle-stimulating hormone correlated with BMD at FN, T and TF. In conclusion, we found a high prevalence of osteopenia and osteoporosis in this population, with weight being the best predictor of BMD. The prevalence of osteoporosis and osteopenia at FN was as high in men as that observed in women.

Absorptiometry, Photon↗
PubMed2005

Effects of creatine supplementation on body composition and renal function in rats.

BACKGROUND: The aim of the present study was to evaluate the long-term effects of oral creatine supplementation on renal function and body composition (fat and lean mass) in an experimental model. METHODS: Male Wistar rats were supplemented with creatine (2 g.kg(-1) of food) for 10 wk in combination with treadmill exercise, 12 m.min(-1), 1 h.d(-1) (CREAT + EX, N = 12) or not (CREAT, N = 10), and compared with exercised animals without creatine supplementation (EX, N = 7) and CONTROL animals, N = 7. Body composition and bone mineral density (BMD) were determined by dual x-ray absorptiometry and glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by inulin and paraaminohippurate clearance, respectively. RESULTS: At the end of the study (post), CREAT+EX presented higher lean mass and lower fat mass than CREAT, EX or CONTROL (349.7 +/- 19.7 vs 313.3 +/- 20.3, 311.9 +/- 30.8, 312.4 +/- 21.0 g and 5.7 +/- 2.3 vs 10.0 +/- 3.3, 9.8 +/- 1.5, 10.0 +/- 3.5%, P < 0.05, respectively). Post lean/fat mass ratio was higher than baseline only in CREAT + EX (18.9 +/- 7.2 vs 8.6 +/- 1.8, P < 0.05). Post BMD was significantly higher than baseline in all groups. GFR and RPF were lower in CREAT versus CONTROL (0.5 +/- 0.1 vs 1.0 +/- 0.1 and 1.5 +/- 0.2 vs 2.4 +/- 0.5 mL.min(-1), P < 0.05, respectively). CONCLUSION: Creatine supplement in combination with exercise increased the proportion of lean mass more than EX or CREAT alone. The use of creatine alone induced an important and significant reduction of both RPF and GFR.

Animals↗
PubMed2005

High degree of discordance between three-dimensional and two-dimensional lumbar spine bone mineral density in Turner's syndrome.

Low bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) has been described in Turner's syndrome (TS). One of the error factors of DXA is short stature, a common finding in TS patients. Aimed to evaluate the influence of a low stature on BMD, we compared the two-dimensional (2D) or conventional BMD (cBMD) with three-dimensional (3D) or volumetric BMD (vBMD) in 62 females (10 to 48 yr old) with TS diagnosis in a case control study. They were compared to 102 normal females (7 to 45 yr old) grouped by age-ranges. All patients were subjected to a lumbar spine densitometry by DXA in the PA and lateral projections, obtained the cBMD and vBMD and calculated for the apparent BMD (appBMD). In TS, the mean of Z-score for cBMD was significantly lower than that for vBMD and for appBMD (-2.31 +/- 1.42; -0.64 +/- 1.55; and -1.72 +/- 1.5; respectively). Most of the patients (83.8%) had a Z-score <-1 for cBMD, whereas the majority (58.1%) had a Z-score <-1 for vBMD. Concluding, the cBMD underestimates the bone mass of the lumbar spine in patients with TS inducing to false diagnoses of bone fragility. Volumetric BMD approached the bone mass of control patients, while appBMD just partially do that.

Absorptiometry, Photon↗