Célia Nogueira

Spectrum of MMACHC mutations in Italian and Portuguese patients with combined methylmalonic aciduria and homocystinuria, cblC type.

Methylmalonic aciduria (MMA) and homocystinuria, cblC type (MIM 277400) is the most frequent inborn error of vitamin B(12). The recent identification of the disease gene, MMACHC, has permitted preliminary genotype-phenotype correlations. We studied 24 Italian and 17 Portuguese patients with cblC defect to illustrate the spectrum of mutations in a southern European population and discuss the impact that mutation identification has on routine diagnostic procedures. Since the metabolic defect raises the serum levels of homocysteine, we also tested if variants in MTHFR-playing a key role in homocysteine remethylation pathway-could act as genetic modifier in cblC defect. We found that the c.271dupA (accounting for 55% of the MMACH alleles in our cohort) followed by c.394C>T (16%) and c.331C>T (9%) were the most frequent mutations. In our study we also identified a novel mutation (c.544T>C). On the other hand, the MTHFR genotype did not appear to influence age at onset, the clinical phenotype and outcome of patients with cblC defect. This study shows that mutation screening for the most common MMACH mutations occurring in early-onset forms (c.271dupA and c.331C>T) seems to have a high diagnostic yield in a southern European population with cblC defect. Although the identification of the gene defect per se does not predict completely time and severity of disease appearance, our data corroborate the importance of a molecular testing to offer accurate prenatal diagnosis to couples at high risk of having affected children.

Qualidade de vida após revascularização cirúrgica do miocárdio, angioplastia ou tratamento clínico

BACKGROUND: Although the clinical benefits of coronary interventions seem to be confirmed, their effects on quality of life (QoL) are still scarcely studied. OBJECTIVE: To assess the QoL in multivessel coronary disease in patients randomly undergoing surgery, angioplasty or medical treatment. METHODS: The Short-Form Health Survey (SF-36) questionnaire was answered by 483 patients. Of these, 161 underwent surgical revascularization, 166 underwent angioplasty, and 153 were medically treated. RESULTS: At baseline, 86% of the patients referred angina, 34% referred infarction, and 32% were smokers. Medical Treatment: 12 patients (7.7%) had AMI, 24 (15.3%) underwent surgery, and 19 (12.1%) died. In addition, 5 (3.2%) had stroke, and 40 (25.6%) had angina. As regards the mental component, 64.1% and 30.8% had their condition improved and worsened, respectively. As regards the physical component, 70.5% and 27.6% had their condition improved and worsened, respectively. Surgery: 13 patients (8.1%) had AMI, 2 (1.2%) underwent surgery, and 12(7.4%) died. Also, 9 (5.6%) had stroke and 30 (18.6%) had angina. As regards the mental component, 72.7 % and 25.5% had their condition improved and worsened, respectively. As regards the physical component, 82.6% and 16.1% had their condition improved and worsened, respectively. Angioplasty: 18 patients (10.9%) had AMI, 51 (30.7%) underwent interventions, and 18 (19.9%) died. Additionally, six (3.6%) presented stroke and 35 (21%) reported angina. As regards the mental component, 66.9% and 26.5% had their condition improved and worsened, respectively. As regards the physical component, 77.1% and 20.5% had their condition improved and worsened, respectively. CONCLUSION: Improvement was observed in all domains and in the three therapeutic modalities. Comparatively, surgery had provided a better quality of life after a four-year follow-up.

Tributyltin chloride leads to adiposity and impairs metabolic functions in the rat liver and pancreas

Tributyltin chloride (TBT) is an environmental contaminant used in antifouling paints of boats. Endocrine disruptor effects of TBT are well established in animal models. However, the adverse effects on metabolism are less well understood. The toxicity of TBT in the white adipose tissue (WAT), liver and pancreas of female rats were assessed. Animals were divided into control and TBT (0.1 μg/kg/day) groups. TBT induced an increase in the body weight of the rats by the 15th day of oral exposure. The weight gain was associated with high parametrial (PR) and retroperitoneal (RP) WAT weights. TBT-treatment increased the adiposity, inflammation and expression of ERα and PPARγ proteins in both RP and PR WAT. In 3T3-L1 cells, estrogen treatment reduced lipid droplets accumulation, however increased the ERα protein expression. In contrast, TBT-treatment increased the lipid accumulation and reduced the ERα expression. WAT metabolic changes led to hepatic inflammation, lipid accumulation, increase of PPARγ and reduction of ERα protein expression. Accordingly, there were increases in the glucose tolerance and insulin sensitivity tests with increases in the number of pancreatic islets and insulin levels. These findings suggest that TBT leads to adiposity in WAT specifically, impairing the metabolic functions of the liver and pancreas.

Qualidade de vida após revascularização cirúrgica do miocárdio com e sem circulação extracorpórea

BACKGROUND: Coronary artery bypass grafting techniques without using cardiopulmonary bypass (off-pump CABG) result in less systemic damage, less clinical complications, less time spent in the intensive care unit, and shorter hospital stays, thereby raising the perspective of improved quality of life (QOL) for patients. OBJECTIVE: To assess quality of life in patients who underwent on-pump and off-pump CABG. METHODS: The Short-Form Health Survey (SF-36) Questionnaire was administered to patients with stable multivessel coronary artery disease (CAD) and preserved ventricular function before and at six and 12 months after surgery. RESULTS: Between January 2002 and December 2006, a total of 202 patients were randomized to either on-pump or off-pump CABG. Demographic, clinical, laboratory, and angiographic characteristics were similar in both groups. One hundred and five patients underwent off-pump CABG and 97 underwent on-pump CABG. In the postoperative course, 22 patients had myocardial infarction, 29 reported angina, one was reoperated, and three experienced stroke. No patient died. Quality of life, as measured by the SF-36 questionnaire, was shown to be similar in both groups regarding physical and mental components. However, male patients showed a significant improvement in physical functioning and role limitations due to physical problems. Also, a large number of patients in both groups returned to work. CONCLUSION: Progressive enhancement in quality of life and early return to work were observed for all patients, regardless of the surgical technique used. Save for a greater improvement in physical functioning and role limitations due to physical problems experienced by male patients, no statistically significant differences were found in the other domains between groups.

Novel TTC19 mutation in a family with severe psychiatric manifestations and complex III deficiency

Complex III of the mitochondrial respiratory chain (CIII) catalyzes transfer of electrons from reduced coenzyme Q to cytochrome c. Low biochemical activity of CIII is not a frequent etiology in disorders of oxidative metabolism and is genetically heterogeneous. Recently, mutations in the human tetratricopeptide 19 gene (TTC19) have been involved in the etiology of CIII deficiency through impaired assembly of the holocomplex. We investigated a consanguineous Portuguese family where four siblings had reduced enzymatic activity of CIII in muscle and harbored a novel homozygous mutation in TTC19. The clinical phenotype in the four sibs was consistent with severe olivo–ponto–cerebellar atrophy, although their age at onset differed slightly. Interestingly, three patients also presented progressive psychosis. The mutation resulted in almost complete absence of TTC19 protein, defective assembly of CIII in muscle, and enhanced production of reactive oxygen species in cultured skin fibroblasts. Our findings add to the array of mutations in TTC19, corroborate the notion of genotype/phenotype variability in mitochondrial encephalomyopathies even within a single family, and indicate that psychiatric manifestations are a further presentation of low CIII.

Syndromes associated with mitochondrial DNA depletion

Mitochondrial dysfunction accounts for a large group of inherited metabolic disorders most of which are due to a dysfunctional mitochondrial respiratory chain (MRC) and, consequently, deficient energy production. MRC function depends on the coordinated expression of both nuclear (nDNA) and mitochondrial (mtDNA) genomes. Thus, mitochondrial diseases can be caused by genetic defects in either the mitochondrial or the nuclear genome, or in the cross-talk between the two. This impaired cross-talk gives rise to so-called nuclear-mitochondrial intergenomic communication disorders, which result in loss or instability of the mitochondrial genome and, in turn, impaired maintenance of qualitative and quantitative mtDNA integrity. In children, most MRC disorders are associated with nuclear gene defects rather than alterations in the mtDNA itself.The mitochondrial DNA depletion syndromes (MDSs) are a clinically heterogeneous group of disorders with an autosomal recessive pattern of transmission that have onset in infancy or early childhood and are characterized by a reduced number of copies of mtDNA in affected tissues and organs. The MDSs can be divided into least four clinical presentations: hepatocerebral, myopathic, encephalomyopathic and neurogastrointestinal. The focus of this review is to offer an overview of these syndromes, listing the clinical phenotypes, together with their relative frequency, mutational spectrum, and possible insights for improving diagnostic strategies.

Modulation of insulin secretion and 45Ca2+ efflux by dopamine in glucose-stimulated pancreatic islets

1. The effect of dopamine on calcium efflux and insulin secretion is examined in the present study. For this purpose, islets isolated from adult Wistar rats were perfused or incubated at 37 degrees C for 60 min. 2. The results obtained from perfused islets indicate that 100 microM dopamine, in the presence of 5.6 mM glucose, increases insulin secretion and causes a modest elevation of 45Ca2+ efflux. However, glucose stimuli (from 5.6 to 16.7 mM) provoked an unexpected reduction of insulin release, with no alteration in calcium efflux, when 100 microM dopamine was present in the perfusion medium. 3. Similar findings were obtained in incubated islets when the prolonged effect of dopamine was investigated. 4. The observations described above led us to conclude that bioactive amines might play an important role in the modulation of the glucose-induced insulin secretion.

Administration of physiologic levels of triiodothyronine increases leptin expression in calorie-restricted obese rats, but does not influence weight loss

Obesity has become a major public health problem, most commonly treated via dietary restriction to promote weight loss. Although leptin and thyroid hormones are involved in the regulation of energy balance, the role of these hormones after the stabilization of weight loss remains unclear. This study was designed to analyze the effect of thyroid hormone on sustained weight loss and leptin gene expression in obese animals after a loss of 5% to 10% of body weight. Thirty-day-old male Wistar rats were separated into 4 groups: control, obese, calorie restriction (CR), and calorie restriction with triiodothyronine administration (CRT). The obese group had increased weight and adiposity, leptin and insulin levels, and leptin gene expression. Dietary restriction in the CR group resulted in decreased body weight and adiposity, diminished leptin, and increased thyroid hormone receptor beta expression. The CRT group, submitted to dietary restriction with concomitant administration of a physiologic triiodothyronine dose, had thyroid hormone receptor beta expression at levels comparable with those observed in the control group and simultaneously increased leptin expression as compared with that in the CR group, suggesting that thyroid hormone modulates leptin expression under conditions of calorie restriction. Increased leptin expression in the CRT group did not result in increased circulating leptin or a statistically significant reduction in body weight during the treatment period. These data provide impetus for further study, as a longer treatment period may result in increased circulating leptin and, thus, further reduction in body weight during calorie restriction in an obesity model.

Obesity is the major cause of alterations in insulin secretion and calcium fluxes by isolated islets from aged rats

To investigate the alterations in insulin secretion induced by aging, 2-month-old, 12-month-old, and 12-month old lean rats (submitted to a caloric restriction during the last month that causes a weight loss of approximately 20%) were studied. As expected, glucose intolerance and increased insulin response were observed during IV-GTT in 12-month-old rats. These effects were, however, reversed by weight loss. Insulin secretion was investigated in isolated islets both during static incubation and perifusion. In 12-month-old rats insulin secretion and 45Ca2+ efflux were lower only in the second phase of the hormonal secretion, suggesting an involvement of voltage-sensitive calcium channels in these phenomena. Considering that in vivo and in vitro alterations were reversed after weight loss, it is possible to conclude that obesity is probably a major cause of impaired insulin secretion in 12-month-old albino rats. Since 14C-glucose metabolism was not changed in islets from aged rats, the effect of obesity on insulin secretion is not due to altered glucose metabolism in pancreatic B-cells.

Prepubertal male pseudohermaphroditism due to 17-ketosteroid reductase deficiency: diagnostic value of a hCG test and lack of HLA association.

Most patients with male pseudohermaphroditism (MPH) due to 17-ketosteroid reductase (17-KSR) deficiency were diagnosed at or after puberty when significant virilization occurred. We report 2 prepubertal sibs (Case 1, 4 yr and Case 2, 10 yr) unambiguously raised as females, with clitoral enlargement, separate urethral and vaginal orifices and gonads palpable at the inguinal canal bilaterally. Basal serum LH, FSH, 17-hydroxyprogesterone, testosterone (T), Dihydrotestosterone and dehydroepiandrosterone (DHEA) were normal for age. †4-Androstenedione (†4-A) was slightly elevated in Case 2 but nondiagnostic. Steroid measurements after human chorionic gonadotropin (hCG) stimulation were compared with those of boys with male external genitalia submitted to the same hCG protocol: peak T was subnormal (Case 1, 80, Case 2, 91, vs normal 329 ± 129 ng/dl, mean ± 1SD), peak †4-A elevated (Case 1, 477, Case 2,264, vs normal 44 ± 26 ng/dl) resulting in an abnormally elevated †4-A/T ratio (Case 1, 6.0, Case 2,2.9, vs normal 0.12 ± 0.09) and establishing the diagnosis of 17-KSR deficiency. This diagnosis was confirmed in vitro by minimal T production when testicular tissue of both patients was incubated with tritiated †4-A. The 2 sibs did not share a single haplotype for the HLA complex indicating lack of association between HLA and the locus of the gene for 17-KSR. In conclusion, in 2 sibs with MPH the subnormal T and elevated †4-A response to the hCG test indicated the diagnosis of 17-KSR deficiency followed by orchiectomy to avoid later virilization at puberty.