Frequency of multiple endocrine neoplasia type 1 in a group of patients with pituitary adenoma: genetic study and familial screening.

The purpose of this study it was to evaluate the frequency of Multiple Endocrine Neoplasia type 1 (MEN1) in patients with pituitary adenoma and to perform genetic analysis and familial screening of those individuals afflicted with MEN1. 144 patients with pituitary adenoma at Botucatu Medical School, UNESP-Univ Estadual Paulista, were assessed retrospectively for MEN1 during the years of 2005-2011. The patients were evaluated for the presence of primary hyperparathyroidism (PHP) and enteropancreatic tumors. Genetic analysis was performed for the individuals with clinically diagnosed MEN1. Thirteen patients met the diagnostic criteria for MEN1, but three individuals belong to the same family and they were considered as a single MEN1 event, revealing 7.7 % frequency of MEN1 in this patient group. Genetic analysis showed MEN1 mutations in four index cases: IVS4+1 G>A, IVS3-6 C>T, c.1547insC and a new D180A mutation. One patient did not agree to participate in the genetic study and another one was referred for follow up in other hospital. Only polymorphisms were found in the other individuals, one of which was novel. We identified a high frequency of MEN1 in pituitary adenoma patients. Since PHP is one of the most common MEN1 tumor and patients are mostly asymptomatic, we suggest that all pituitary adenoma patients have their calcium profile analyzed.

Supraphysiological triiodothyronine doses diminish leptin and adiponectin gene expression, but do not alter resistin expression in calorie restricted obese rats.

Thyroid hormones regulate energy balance and act on adipokines. However, while it is unclear what the effects are of calorie restriction and high doses of triiodothyronine (T(3)) on adipokines in obesity, thyroid hormones are illicitly administered in isolation or in association with a hypocaloric diet as an obesity treatment. The present study determined the effect of T(3) on serum concentrations and gene expression of the adipokines leptin, resistin, and adiponectin in calorie-restricted obese rats. Male Wistar rats received a hypercaloric diet for 20 weeks followed by calorie restriction for 8 weeks. The animals were then randomly divided into 3 groups: calorie restriction (OR), OR with 5 µg of T(3)/100 g BW (RS1), and OR with 25 µg of T(3)/100 g BW (RS2) for 2 weeks. Blood and adipose tissue samples were collected for biochemical, hormonal, and gene expression analyses. Serum concentrations of leptin (OR: 3.7±0.6, RS1: 3.8±1, RS2 0.2±0.07 ng/dl) and resistin (OR: 2.5±0.6, RS1: 2.5±0.5, RS2 1.6±0.3 ng/dl) were diminished at the higher dose, while serum adiponectin (OR: 31±7, RS1: 24±5, RS2 26±7 ng/dl) levels were lower in the low dose group. Administration of T(3) reduced leptin gene expression (OR: 0.91±0.1, RS1: 0.95±0.1, RS2 0.22±0.1) only at the higher dose, resistin expression (OR: 1.06±0.2, RS1: 1.04±0.1, RS2 0.88±0.2) was not influenced by T(3) treatment, and adiponectin expression (OR: 1.55±0.5, RS1: 0.95±0.15, RS2 0.97±0.13) was diminished independent of the T(3) dose. These results indicate that T(3), directly or indirectly, inhibits the expression of leptin and adiponectin in calorie restricted obese animals.

Relationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exercise.

We determined the response characteristics and functional correlates of the dynamic relationship between the rate (Δ) of oxygen consumption (VO(2)) and the applied power output (work rate = WR) during ramp-incremental exercise in patients with mitochondrial myopathy (MM). Fourteen patients (7 males, age 35.4 ± 10.8 years) with biopsy-proven MM and 10 sedentary controls (6 males, age 29.0 ± 7.8 years) took a ramp-incremental cycle ergometer test for the determination of the VO(2) on-exercise mean response time (MRT) and the gas exchange threshold (GET). The ΔVO(2)/ΔWR slope was calculated up to GET (S(1)), above GET (S(2)) and over the entire linear portion of the response (S(T)). Knee muscle endurance was measured by isokinetic dynamometry. As expected, peak VO(2) and muscle performance were lower in patients than controls (P < 0.05). Patients had significantly lower ΔVO(2)/ΔWR than controls, especially the S(2) component (6.8 ± 1.5 vs 10.3 ± 0.6 mL·min(-1)·W(-1), respectively; P < 0.001). There were significant relationships between ΔVO(2)/ΔWR (S(T)) and muscle endurance, MRT-VO(2), GET and peak VO(2) in MM patients (P < 0.05). In fact, all patients with ΔVO(2)/ΔWR below 8 mL·min(-1)·W(-1) had severely reduced peak VO(2) values (<60% predicted). Moreover, patients with higher cardiopulmonary stresses during exercise (e.g., higher Δ ventilation/carbon dioxide output and Δ heart rate/ΔVO(2)) had lower ΔVO(2)/ΔWR (P < 0.05). In conclusion, a readily available, effort-independent index of aerobic dysfunction during dynamic exercise (ΔVO(2)/ΔWR) is typically reduced in patients with MM, being related to increased functional impairment and higher cardiopulmonary stress.

Relationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exercise

We determined the response characteristics and functional correlates of the dynamic relationship between the rate (Δ) of oxygen consumption ( VO2) and the applied power output (work rate = WR) during ramp-incremental exercise in patients with mitochondrial myopathy (MM). Fourteen patients (7 males, age 35.4 ± 10.8 years) with biopsy-proven MM and 10 sedentary controls (6 males, age 29.0 ± 7.8 years) took a ramp-incremental cycle ergometer test for the determination of the VO2 on-exercise mean response time (MRT) and the gas exchange threshold (GET). The ΔVO2/ΔWR slope was calculated up to GET (S1), above GET (S2) and over the entire linear portion of the response (S T). Knee muscle endurance was measured by isokinetic dynamometry. As expected, peak VO2 and muscle performance were lower in patients than controls (P < 0.05). Patients had significantly lower ΔVO2/ΔWR than controls, especially the S2 component (6.8 ± 1.5 vs 10.3 ± 0.6 mL·min-1·W-1, respectively; P < 0.001). There were significant relationships between ΔVO2/ΔWR (S T) and muscle endurance, MRT-VO2, GET and peak VO2 in MM patients (P < 0.05). In fact, all patients with ΔVO2/ΔWR below 8 mL·min-1·W-1 had severely reduced peak VO2 values (<60 percent predicted). Moreover, patients with higher cardiopulmonary stresses during exercise (e.g., higher Δ ventilation/carbon dioxide output and Δ heart rate/ΔVO2) had lower ΔVO2/ΔWR (P < 0.05). In conclusion, a readily available, effort-independent index of aerobic dysfunction during dynamic exercise (ΔVO2/ΔWR) is typically reduced in patients with MM, being related to increased functional impairment and higher cardiopulmonary stress.

Serum levels of selenium in patients with breast cancer before and after treatment of external beam radiotherapy.

BACKGROUND: To evaluate the influence of radiotherapy on the selenium serum levels of breast cancer patients. PATIENTS AND METHODS: This prospective study includes 209 breast cancer patients treated by external beam radiotherapy from December 2007 until August 2008. Plasma selenium concentrations were determined before and at the end of the radiotherapeutic treatment. Age, clinical stage, prior chemotherapy, body mass index (BMI) and personal habits (smoking and alcoholism) were recorded for each patient. RESULTS: The mean age was 61 years; the mean BMI was 28.7. One hundred and seventy-four patients (83.3%) were nonsmokers. One hundred and eighty-nine patients (90.4%) showed no drinking habits and 110 (52.6%) have no prior chemotherapy. Sixty patients (28.7%) were in clinical stage I, 141 (67.5%) in clinical stage II and 8 (3.8%) in clinical stage III. At the beginning of radiotherapy, the mean selenium value for all patients was 86.4 µg/l and after radiation this value dropped to 47.8 µg/l. Multivariate analysis showed statistically significant difference in the plasma selenium concentration before and after radiotherapy for age (P > 0.001), BMI (P > 0.001), smoking (P > 0.001), alcoholism (P > 0.001), chemotherapy (P > 0.001) and clinical stage (P > 0.001). CONCLUSIONS: Significant reduction in plasma levels of selenium is recorded in patients undergoing radiotherapy, suggesting attention to the nutritional status of this micronutrient and other antioxidant agents.

Obesity induces upregulation of genes involved in myocardial Ca2+ handling.

Obesity is a complex multifactorial disorder that is often associated with cardiovascular diseases. Research on experimental models has suggested that cardiac dysfunction in obesity might be related to alterations in myocardial intracellular calcium (Ca2+) handling. However, information about the expression of Ca2+-related genes that lead to this abnormality is scarce. We evaluated the effects of obesity induced by a high-fat diet in the expression of Ca2+-related genes, focusing the L-type Ca2+ channel (Cacna1c), sarcolemmal Na+/Ca2+ exchanger (NCX), sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), ryanodine receptor (RyR2), and phospholamban (PLB) mRNA in rat myocardium. Male 30-day-old Wistar rats were fed a standard (control) or high-fat diet (obese) for 15 weeks. Obesity was defined as increased percent of body fat in carcass. The mRNA expression of Ca2+-related genes in the left ventricle was measured by RT-PCR. Compared with control rats, the obese rats had increased percent of body fat, area under the curve for glucose, and leptin and insulin plasma concentrations. Obesity also caused an increase in the levels of SERCA2a, RyR2 and PLB mRNA (P < 0.05) but did not modify the mRNA levels of Cacna1c and NCX. These findings show that obesity induced by high-fat diet causes cardiac upregulation of Ca2+ transport_related genes in the sarcoplasmic reticulum.

Obesity induces upregulation of genes involved in myocardial Ca2+ handling

Obesity is a complex multifactorial disorder that is often associated with cardiovascular diseases. Research on experimental models has suggested that cardiac dysfunction in obesity might be related to alterations in myocardial intracellular calcium (Ca2+) handling. However, information about the expression of Ca2+-related genes that lead to this abnormality is scarce. We evaluated the effects of obesity induced by a high-fat diet in the expression of Ca2+-related genes, focusing the L-type Ca2+ channel (Cacna1c), sarcolemmal Na+/Ca2+ exchanger (NCX), sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), ryanodine receptor (RyR2), and phospholamban (PLB) mRNA in rat myocardium. Male 30-day-old Wistar rats were fed a standard (control) or high-fat diet (obese) for 15 weeks. Obesity was defined as increased percent of body fat in carcass. The mRNA expression of Ca2+-related genes in the left ventricle was measured by RT-PCR. Compared with control rats, the obese rats had increased percent of body fat, area under the curve for glucose, and leptin and insulin plasma concentrations. Obesity also caused an increase in the levels of SERCA2a, RyR2 and PLB mRNA (P < 0.05) but did not modify the mRNA levels of Cacna1c and NCX. These findings show that obesity induced by high-fat diet causes cardiac upregulation of Ca2+ transport_related genes in the sarcoplasmic reticulum.

Tamoxifen inhibits transforming growth factor-alpha gene expression in human breast carcinoma samples treated with triiodothyronine.

OBJECTIVES: To examine the effects of triiodothyronine (T3), 17beta-estradiol (E2), and tamoxifen (TAM) on transforming growth factor (TGF)-alpha gene expression in primary breast cancer cell cultures and interactions between the different treatments. METHODS AND RESULTS: Patients included in the study (no.=12) had been newly diagnosed with breast cancer. Fresh human breast carcinoma tissue was cut into 0.3- mm slices. These slices were placed in six 35-mm dishes on 2-ml organ culture medium. Dishes received the following treatments: dish 1: ethanol; dish 2: T3; dish 3: T3+TAM; dish 4: TAM; dish 5: E2; dish 6: E2+TAM. TGF-alpha mRNA content was normalized to glyceraldehyde-3-phosphate dehydrogenase mRNA levels. All tissues included in this study were positive for estrogen receptor (ER) and thyroid hormone receptor expression. Treatment with T3 for 48 h significantly increased TGF-alpha mRNA levels compared to controls (15-fold), and concomitant treatment with TAM reduced expression to 3.4-fold compared to controls. When only TAM was added to the culture medium, TGF-alpha mRNA expression increased 5.3-fold, significantly higher than with all other treatment modalities. CONCLUSION: We demonstrate that TGF-alpha mRNA expression is more efficiently upregulated by T3 than E2. Concomitant treatment with TAM had a mitigating effect on the T3 effect, while E2 induced TGF-alpha upregulation. Our findings show some similarities between primary culture and breast cancer cell lines, but also some important differences: a) induction of TGF-alpha, a mitogenic protein, by TAM; b) a differential effect of TAM that may depend on relative expression of ER alpha and beta; and c) supraphysiological doses of T3 may induce mitogenic signals in breast cancer tissue under conditions of low circulating E2.

Down-regulation of the cardiac sarcoplasmic reticulum ryanodine channel in severely food-restricted rats.

We have shown that myocardial dysfunction induced by food restriction is related to calcium handling. Although cardiac function is depressed in food-restricted animals, there is limited information about the molecular mechanisms that lead to this abnormality. The present study evaluated the effects of food restriction on calcium cycling, focusing on sarcoplasmic Ca2+-ATPase (SERCA2), phospholamban (PLB), and ryanodine channel (RYR2) mRNA expressions in rat myocardium. Male Wistar-Kyoto rats, 60 days old, were submitted to ad libitum feeding (control rats) or 50% diet restriction for 90 days. The levels of left ventricle SERCA2, PLB, and RYR2 were measured using semi-quantitative RT-PCR. Body and ventricular weights were reduced in 50% food-restricted animals. RYR2 mRNA was significantly decreased in the left ventricle of the food-restricted group (control = 5.92 +/- 0.48 vs food-restricted group = 4.84 +/- 0.33, P < 0.01). The levels of SERCA2 and PLB mRNA were similar between groups (control = 8.38 +/- 0.44 vs food-restricted group = 7.96 +/- 0.45, and control = 1.52 +/- 0.06 vs food-restricted group = 1.53 +/- 0.10, respectively). Down-regulation of RYR2 mRNA expressions suggests that chronic food restriction promotes abnormalities in sarcoplasmic reticulum Ca2+ release.

Down-regulation of the cardiac sarcoplasmic reticulum ryanodine channel in severely food-restricted rats

We have shown that myocardial dysfunction induced by food restriction is related to calcium handling. Although cardiac function is depressed in food-restricted animals, there is limited information about the molecular mechanisms that lead to this abnormality. The present study evaluated the effects of food restriction on calcium cycling, focusing on sarcoplasmic Ca2+-ATPase (SERCA2), phospholamban (PLB), and ryanodine channel (RYR2) mRNA expressions in rat myocardium. Male Wistar-Kyoto rats, 60 days old, were submitted to ad libitum feeding (control rats) or 50 percent diet restriction for 90 days. The levels of left ventricle SERCA2, PLB, and RYR2 were measured using semi-quantitative RT-PCR. Body and ventricular weights were reduced in 50 percent food-restricted animals. RYR2 mRNA was significantly decreased in the left ventricle of the food-restricted group (control = 5.92 ± 0.48 vs food-restricted group = 4.84 ± 0.33, P < 0.01). The levels of SERCA2 and PLB mRNA were similar between groups (control = 8.38 ± 0.44 vs food-restricted group = 7.96 ± 0.45, and control = 1.52 ± 0.06 vs food-restricted group = 1.53 ± 0.10, respectively). Down-regulation of RYR2 mRNA expressions suggests that chronic food restriction promotes abnormalities in sarcoplasmic reticulum Ca2+ release.

Mandible analysis in sex steroid-deficient rats.

The aim of this study was to evaluate, by morphologic techniques, the effects of sex steroid deficiency on mandible bone remodeling of female rats, in groups of different experimental periods and to compare the results with 90-day orquiectomized males. Female and male Wistar rats, 3 months old, were divided into experimental groups and at the end of each experimental period were killed, and mandibles were extracted. The left mandibles were prepared with rote technique bone and examined by a light microscope. Morphological analyses of the mandibles demonstrated resorption signals in the alveolar bone, after 30 days in ovariectomized females, but it was more intense 90 days after castration. The orquiectomized group exhibited some signals of resorption similar to the ovariectomized group of 60 days. Morphometric analysis of alveolar bone thickness in females after 60 days was in agreement with morphological results. However, the analysis of periodontal ligament thickness did not show any significant difference. There were variations in sexual hormone deficiency in the mandibles of males and females and they seemed to be more precocious in ovariectomized than in orquiectomized rats. It is important for a health professional to have knowledge about bone metabolism to improve the quality of life of postmenopaused and old people.

Evaluation of levetiracetam effects on pilocarpine-induced seizures: cholinergic muscarinic system involvement.

Levetiracetam (LEV) is a new antiepileptic drug effective as adjunctive therapy for partial seizures. It displays a unique pharmacological profile against experimental models of seizures, including pilocarpine-induced seizures in rodents. Aiming to clarify if anticonvulsant activity of LEV occurs due to cholinergic alterations, adult male mice received LEV injections before cholinergic agonists' administration. Pretreatment with LEV (30-200 mg/kg, i.p.) increased the latencies of seizures, but decreased status epilepticus and death on the seizure model induced by pilocarpine, 400 mg/kg, s.c. (P400). LEV (LEV200, 200 mg/kg, i.p.) pretreatment also reduced the intensity of tremors induced by oxotremorine (0.5 mg/kg, i.p). [3H]-N-methylscopolamine-binding assays in mice hippocampus showed that LEV200 pretreatment reverts the downregulation on muscarinic acetylcholine receptors (mAChR), induced by P400 administration, bringing back these density values to control ones (0.9% NaCl, i.p.). However, subtype-specific-binding assays revealed that P400- and LEV-alone treatments result in M1 and M2 subtypes decrease, respectively. The agonist-like behavior of LEV on the inhibitory M2 mAChR subtype, observed in this work, could contribute to explain the reduction on oxotremorine-induced tremors and the delay on pilocarpine-induced seizures, by an increase in the attenuation of neuronal activity mediated by the M1 receptors.

Profile of thyroid hormones in breast cancer patients.

Estrogen involvement in breast cancer has been established; however, the association between breast cancer and thyroid diseases is controversial. Estrogen-like effects of thyroid hormone on breast cancer cell growth in culture have been reported. The objective of the present study was to determine the profile of thyroid hormones in breast cancer patients. Serum aliquots from 26 patients with breast cancer ranging in age from 30 to 85 years and age-matched normal controls (N = 22) were analyzed for free triiodothyronine (T3F), free thyroxine (T4F), thyroid-stimulating hormone (TSH), antiperoxidase antibody (TPO), and estradiol (E2). Estrogen receptor ss (ERss) was determined in tumor tissues by immunohistochemistry. Thyroid disease incidence was higher in patients than in controls (58 vs 18%, P < 0.05). Subclinical hyperthyroidism was the most frequent disorder in patients (31%); hypothyroidism (8%) and positive anti-TPO antibodies (19%) were also found. Subclinical hypothyroidism was the only dysfunction (18%) found in controls. Hyperthyroidism was associated with postmenopausal patients, as shown by significantly higher mean T3 and T4 values and lower TSH levels in this group of breast cancer patients than in controls. The majority of positive ERss tumors were clustered in the postmenopausal patients and all cases presenting subclinical hyperthyroidism in this subgroup concomitantly exhibited Erss-positive tumors. Subclinical hyperthyroidism was present in only one of 6 premenopausal patients. We show here that postmenopausal breast cancer patients have a significantly increased thyroid hormone/E2 ratio (P < 0.05), suggesting a possible tumor growth-promoting effect caused by this misbalance.

Profile of thyroid hormones in breast cancer patients

Estrogen involvement in breast cancer has been established; however, the association between breast cancer and thyroid diseases is controversial. Estrogen-like effects of thyroid hormone on breast cancer cell growth in culture have been reported. The objective of the present study was to determine the profile of thyroid hormones in breast cancer patients. Serum aliquots from 26 patients with breast cancer ranging in age from 30 to 85 years and age-matched normal controls (N = 22) were analyzed for free triiodothyronine (T3F), free thyroxine (T4F), thyroid-stimulating hormone (TSH), antiperoxidase antibody (TPO), and estradiol (E2). Estrogen receptor ß (ERß) was determined in tumor tissues by immunohistochemistry. Thyroid disease incidence was higher in patients than in controls (58 vs 18 percent, P < 0.05). Subclinical hyperthyroidism was the most frequent disorder in patients (31 percent); hypothyroidism (8 percent) and positive anti-TPO antibodies (19 percent) were also found. Subclinical hypothyroidism was the only dysfunction (18 percent) found in controls. Hyperthyroidism was associated with postmenopausal patients, as shown by significantly higher mean T3 and T4 values and lower TSH levels in this group of breast cancer patients than in controls. The majority of positive ERß tumors were clustered in the postmenopausal patients and all cases presenting subclinical hyperthyroidism in this subgroup concomitantly exhibited Erß-positive tumors. Subclinical hyperthyroidism was present in only one of 6 premenopausal patients. We show here that postmenopausal breast cancer patients have a significantly increased thyroid hormone/E2 ratio (P < 0.05), suggesting a possible tumor growth-promoting effect caused by this misbalance.

Low triiodothyronine (T3) or reverse triiodothyronine (rT3) syndrome modifies gene expression in rats with congestive heart failure.

Heart failure (HF) is frequently associated with euthyroid "sick" syndrome (low T3 and elevated rT3). We investigated if altered thyroid hormone in HF could affect expression of the TH receptor (TRalpha1), and alpha and beta myosin heavy chains (alpha-MHC, beta-MHC). HF was provoked in rats by aortic stenosis. We showed that rT3 generated from liver and kidney deiodination significantly increased and T3 decreased in HF; there was significantly higher TRalpha1 expression, no alpha-MHC expression, but beta-MHC expression. Changes in TRalpha could be compensating for low T3 from HF.

Tumor grade heterogeneity in urothelial bladder carcinoma--proposal of a system using combined numbers.

OBJECTIVE: There is no consensus for grading when more than one grade is present in bladder carcinoma. We propose a grading system that considers the primary (most common) and secondary (second most common) grade of bladder cancer. Grade was correlated with stage of the tumors. MATERIAL AND METHODS: We studied 293 bladder transurethral resections or radical cystectomies. Grade was considered as 1, 2 or 3 according to the 1999 World Health Organization system. The number was repeated when only one grade was seen. A final score was obtained which ranged from 2 to 6. All cases were also graded according to the highest grade area even if it was focal. RESULTS: According to the highest grade area, the distribution was 80 (74.07%), 27 (25.00%) and 1 (0.92%) for grade 1; 31 (24.03%), 69 (53.48%) and 29 (22.48%) for grade 2; and 0 (0%), 17 (30.35%) and 39 (69.64%) for grade 3, corresponding to the stages Ta, T1 and T2-T3, respectively. Using the system of combined numbers, grade 2 was stratified into subgroups 1 + 2 and 2 + 2 which are statistically different (p < 0.05) when considering stage. In grade 3, there was also a trend for statistical difference (p = 0.066) between grades 2 + 3 and 3 + 3. CONCLUSIONS: The grading system of combined numbers, stratifies grade 2 into subgroups 1 + 2 and 2 + 2, and grade 3 into subgroups 2 + 3 and 3 + 3 which are statistically different when considering stage. This grading system of combined numbers takes into consideration tumor heterogeneity and may be of value in prospective studies for analysis of prognosis and therapeutic response.

A novel mutation (Q40P) in PAX8 associated with congenital hypothyroidism and thyroid hypoplasia: evidence for phenotypic variability in mother and child.

Congenital hypothyroidism associated with thyroid hypoplasia can be caused by several genetic defects, including mutations in the TSHbeta-subunit, the TSH receptor, the G(s)alpha-subunit, and the transcription factor PAX8. Four girls with sporadic congenital hypothyroidism and hypoplastic thyroid glands were analyzed for mutations in PAX8 and TTF2 (FKHL15). Mutations in the coding region of the TSHbeta-subunit gene, the TSH receptor gene, and exons 8 and 9 of G(s)alpha had been excluded previously. Serum TSH concentrations were 150 mU/liter or more, TG levels were within normal limits, and thyroid autoantibodies were absent. Technetium scintigraphies did not reveal the presence of thyroid tissue, but ultrasonography documented hypoplastic, normally located glands. One patient was found to harbor a heterozygous transversion 119A-->C in exon 3 of PAX8 replacing a conserved glutamine by proline in the paired box domain (Q40P). Analysis of her family members revealed that her mother, who has a thyroid gland of normal size and mild, adult-onset autoimmune hypothyroidism, is also heterozygous for this mutation. Functional analyses of the PAX8 Q40P mutation showed impaired binding to a PAX8 response element and absent trans-activation of a thyroid peroxidase promoter luciferase reporter gene. These findings confirm the important role of PAX8 in the development of the thyroid, but they indicate that PAX8 gene mutations may have a variable penetrance or expressivity. The absence of mutations in the coding sequences of the analyzed genes in the three other patients supports the concept that the pathogenesis of congenital hypothyroidism associated with thyroid hypoplasia is diverse.

Clinical and laboratory evaluation of hyperlipemic and hypothyroid patients.

OBJECTIVE: To determine the frequency of hypothyroidism in a sample of hyperlipemic patients and evaluate clinical and laboratory factors indicative of thyropathy among them. METHODS: Fifty-one hyperlipemic patients, grouped according to an earlier or recent diagnosis of their thyroid function into euthyroid and hypothyroid, were evaluated with clinical and laboratory examinations of blood levels of free T4 and TSH (by radioimmunoassay). Patients were on average 46.8 +/- 11.7 years old, predominantly of the female sex (62.5 %); 31 % had a previous diagnosis of hypothyroidism and were under treatment with thyroxin. RESULTS: Fourteen three percent of patients analyzed had hypothyroidism, which had not been detected before. Differentiating attributes of the groups analyzed were: a predominance of females among the hypothyroid patients and a higher HDL serum concentration among those recently diagnosed. CONCLUSION: In the present study, new cases of hypothyroidism in hyperlipemic patients were a frequent occurrence, yet few clinical and laboratory data except tests evaluating free T4 and TSH in the blood indicated which patients had thyroid dysfunction.

Thyrotropin receptor mutations in hyperfunctioning thyroid adenomas from Brazil.

Constitutively activating mutations in the thyrotropin (TSH) receptor have been identified as a major molecular cause of hyperfunctioning thyroid adenomas. A smaller subset of these benign tumors is caused by constitutive activation of the adenylyl cyclase cascade by somatic mutations in the Gsalpha gene. In this study, we analyzed hyperfunctioning thyroid adenomas from seven Brazilian patients for TSH receptor and G(s)alpha gene mutations. Solitary autonomous thyroid adenomas were identified by ultrasound and scintigraphy, and DNA was extracted from adenomatous and periadenomatous tissue. Exons 9 and 10 of the TSH receptor gene, and exons 8 and 9 of the G(s)alpha gene, were amplified by polymerase chain reaction (PCR) and subjected to direct sequence analysis. Six of seven adenomas harbored heterozygous mutations known to confer constitutive activity to the TSH receptor. In one case, aspartate 619 was substituted by glycine (D619G). In four adenomas, alanine 623 was replaced by valine (A623V). Both residues are located in the third intracellular loop. In one instance, aspartate 633 located in the sixth transmembrane domain was replaced by tyrosine (D633Y). In this patient, one allele also contained a change of aspartate 727 to glutamate (D727E). This substitution is thought to be a polymorphic variant of the wild-type but it has also been associated with toxic multinodular goiters. Functional comparison of D727 with E727 did not reveal differences in basal or TSH-stimulated cyclic adenosine monophosphate (cAMP)-dependent luciferase activity in transiently transfected cells. These results demonstrate a high prevalence of activating TSH receptor mutations in toxic adenomas in this small series from Brazil (approximately 86%). These findings are in agreement with reports from other countries with a marginal iodine intake but contrast with studies from regions with a high iodine intake where these mutations appear to be less prevalent.

Structural analysis of the thyrotropin receptor in four patients with congenital hypothyroidism due to thyroid hypoplasia.

Sporadic congenital hypothyroidism is most commonly caused by developmental abnormalities of the thyroid gland. More rarely, it is due to defects in gene products involved in the regulation of the hypothalamic-pituitary-thyroid axis or thyroid hormone synthesis. Loss of function mutations in the thyrotropin (TSH) receptor have been shown to result in resistance to biologically active TSH. In complete resistance to TSH, the thyroid gland is hypoplastic and unable to synthesize and secrete sufficient amounts of thyroid hormones. In partial resistance, referred to as euthyroid hyperthyrotropinemia, the size of the gland and the thyroid hormone levels are normal at the expense of an elevated TSH. Four patients with sporadic congenital hypothyroidism and properly located hypoplastic thyroid glands were included in this study. Serum TSH concentrations were 150 mU/L or higher, serum thyroglobulin levels were within normal limits (6.1 to 8.2 ng/mL; normal range: 2.1 to 32 ng/mL), and thyroid autoantibodies were absent. The coding region of the TSHbeta subunit gene, the TSH receptor gene, and exons 8 and 9 of Gsalpha were analyzed by direct sequencing and found to be normal in all patients. One patient was heterozygous for a G to A transition in the TSHbeta gene resulting in a substitution of alanine by threonine at position -7 of the signal peptide. This substitution was also found in her euthyroid father. In addition, Southern analysis of the TSH receptor gene excluded major structural alterations. These findings support previous reports that indicate that TSH resistance is genetically heterogeneous. In addition to mutations in the TSH receptor or the Gsalpha genes, other genetic defects can lead to an identical phenotype. These observations also suggest that TSH receptor mutations might be a relatively rare cause of congenital thyroid hypoplasia.