Mário Henrique Girão Faria

Expression of Ki-67, Topoisomerase IIα and c-MYC in astrocytic tumors: Correlation with the histopathological grade and proliferative status

Astrocytomas represent the most frequent primary tumors of the central nervous system. Recently, the determination of the proliferative index of astrocytic tumors by different methods has been proposed as a valuable tool for tumor grading and also as a prognostic marker. The aim of the present study was to evaluate the expression of cell proliferation‐related proteins in human astrocytic tumors of different histopathological grades (WHO). An immunohistochemical study of the Ki‐67, Topoisomerase IIα (Topo IIα) and c‐MYC proteins using the avidin‐biotin‐peroxidase method was performed in 55 astrocytomas (13 grade I, 14 grade II, 7 grade III and 21 grade IV) and five samples of non‐tumor brain tissue (control group). Ki‐67, Topo IIα and c‐MYC positive indices tended to increase according to malignant progression, were absent in non‐tumor brain tissue and showed maximum values in high‐grade astrocytomas (III and IV). A gradual increase in Ki‐67 antigen expression was observed in agreement with mitotic index and histopathological classification. The same was not observed for Topo IIα and c‐MYC. Ki‐67 antigen detection in more than 8.0% of the tumor cells distinguished astrocytoma grade IV, while a labeling index between 1.5 and 8.0% characterized astrocytomas grade III and values below 1.5% discriminated low‐grade tumors (I and II). These results indicate that Topo IIα and c‐MYC expression is associated with cell proliferation in astrocytomas, although not in an exclusive way. Moreover, Ki‐67 antigen was found to be the best marker of cellular proliferation, and its expression predicts the grade of astrocytic tumors.

The pterional craniotomy: tips and tricks

This review intended to describe in a didactic and practical manner the frontotemporosphenoidal craniotomy, which is usually known as pterional craniotomy and constitute the cranial approach mostly utilized in the modern neurosurgery. This is, then, basically a descriptive text, divided according to the main stages involved in this procedure, and describes with details how the authors currently perform this craniotomy.

Glucocorticoid and calcitonin receptor expression in central giant cell lesions: implications for therapy.

Central giant cell lesion is an uncommon benign jaw lesion, with uncertain aetiology, and variable clinical behaviour. Studies of molecular markers may help to understand the nature and behaviour of this lesion, and eventually may represent a target for pharmacological approaches to treatment. The aim of this study was to analyse the expression of glucocorticoid and calcitonin receptors in central giant cell lesions before and after treatment with intralesional steroid. Paraffin-embedded blocks from patients who underwent treatment with intralesional triamcinolone hexacetonide injections were stained immunohistochemically. Biological material from patients who underwent a surgical procedure after treatment were tested immunohistochemically. 18 cases (9 aggressive and 9 non-aggressive) were included. The difference in calcitonin receptor expression was not statistically significant between the aggressive and non-aggressive lesions and between the patients with a good response and those with a moderate/negative response to treatment. Glucocorticoid receptor expression in the multinucleated giant cells was higher in patients with a good response. It can be postulated that immunohistochemical staining for glucocorticoid receptors may provide a tool for selecting the therapeutic strategy. An H-score greater than 48 for glucocorticoid receptors in multinucleated giant cells predicted a good response in this study.

Angiogenesis inhibition by green propolis and the angiogenic effect of L-lysine on bladder cancer in rats

PURPOSE To determine the effects of water-soluble derivative of green propolis in bladder cancer angiogenesis in rats given N-butyl-(-4-hydroxybutyl) nitrosamine (BBN). METHODS Nine groups were established, where six of them (Groups 1 to 6), the animals received 0.05% BBN in their drinking water for 14 weeks. From the 32nd to the 40th week, Groups 1, 2, 3 and 4 were treated respectively with water, L-lysine (300 mg/kg/day), celecoxib (30 mg/kg/day) and propolis (300 mg/kg/day). Groups 5 and 6 were given propolis and L-lysine from the 1st to the 40th week (150 mg/kg/day). Microvascular density was determined by histological sections stained for the marker CD-31 and analyzed with specific software. RESULTS The microvascular density in bladder carcinomas was lower (p<0.01) in rats receiving propolis than in controls given carcinogen only. On the other hand, the microvascular density of tumors in rats receiving carcinogen and L-lysine for 40 weeks from the beginning of carcinogen treatment was significantly higher (p<0.01) than in the corresponding controls. CONCLUSION Water-soluble derivative of propolis inhibits angiogenesis in BBN-induced rat bladder cancer, while L-lysine treatment stimulates angiogenesis if initiated concurrently with BBN.

c-MYC amplification and expression in astrocytic tumors

The aim of this study was to evaluate the nuclear and cytoplasmic expression of c-MYC protein in human astrocytic tumors of different histopathological grades and to determine whether its expression correlates with c-MYC gene amplification. An immunohistochemical study of c-MYC protein was performed in 140 paraffin-embedded astrocytic tumors of different grades. Among them, 30 specimens were analyzed for c-MYC gene amplification by FISH. Expression of nuclear and cytoplasmic c-MYC was observed, respectively, in 65.0 and 66.4% of the cases studied. The distribution of the positive cases according to the tumor grade increased in both nuclear and cytoplasmic staining with malignancy. The median nuclear LI also increased with tumor grade, with highest c-MYC nuclear expression in grade III. The median cytoplasmic labeling scores showed a significant difference between grade I tumors and diffuse tumors, which presented high and similar median scores. Cytoplasmic c-MYC localization was linked to high nuclear c-MYC expression. FISH results disclosed that the presence of two signals was inversely correlated with histopathological grade, while the presence of ≥5 signals increased according to degree of malignancy. Moreover, the presence of two signals was associated with low nuclear LI and the presence of four or more signals with high nuclear LI. These results indicate that c-MYC expression in astrocytic tumors is strongly associated with increased c-MYC gene copy number and suggest that c-MYC plays a role in the early tumorigenesis of astrocytomas.

A novel TBX5 missense mutation (V263M) in a family with atrial septal defects and postaxial hexodactyly

BACKGROUND Congenital heart diseases are the most frequent birth defects and are commonly associated with skeletal malformations. Mutations in the TBX5 gene, a T-box transcription factor located on chromosome 12q24.1, have been demonstrated to be the underlying molecular alteration in individuals with different congenital cardiac disorders, notably the Holt-Oram syndrome. METHODS Six members from a two-generation family from a consanguineous couple, which had atrial septal defects associated with postaxial hexodactyly in all extremities were clinically assessed and submitted to TBX5 mutational analysis performed by direct sequencing. RESULTS We detected a new TBX5 missense mutation (V263M) in all four individuals studied with cardiac abnormalities. The genotype-phenotype correlations in light of unusual features are extensively discussed, as well as the possible significance of these atypical findings. CONCLUSIONS These new data extend our clinical and molecular knowledge of TBX5 gene mutations and also raise interesting questions about the phenotype heterogeneity regarding these gene alterations.

Ketone bodies metabolism during ischemic and reperfusion brain injuries following bilateral occlusion of common carotid arteries in rats

PURPOSE To evaluate the in vivo alterations on ketone bodies metabolism after cerebral ischemia/reperfusion through an experimental model of brain ischemia induced by simple occlusion of common carotid arteries (CCAs) in Wistar rats. METHODS Forty-eight male Wistar rats were randomly distributed on two groups (S - Sham; T - Test) and further redistributed into four times sets of study. After bilateral occlusion of CCAs for 30 min, the animals of group T were allowed reperfusion for 0, 5, 10 and 15 min. Samples of cerebral tissue and systemic arterial blood were collected and the metabolites acetoacetate (ACT) and beta-hydroxybutyrate (BHB) were determined. RESULTS Cerebral ACT and BHB levels increased significantly in Group T after 30 min of carotid occlusion (time 0). The highest brain ketone bodies (ACT+BHB) concentration was verified at 5 min of reperfusion, decreasing after 10 min of recirculation. Systemic ketone bodies levels increased similarly between test and sham groups. Group S demonstrated a significant increase in cerebral and systemic ACT and BHB concentrations mainly after 40-45 min of study. CONCLUSIONS The partial transient acute global brain ischemia induced by the bilateral carotid occlusion in Wistar rats triggered ketogenesis probably due to a central stimulation of catecholamine secretion. There was an increased cerebral uptake of ketone bodies following brain ischemia, reaffirming these metabolites as alternative energy substrates under conditions of cerebral metabolic stress as well as its potential role on neuroprotection. The greatest changes in ketone bodies metabolism were verified at initial minutes of recirculation as a result of the reperfusion injury phenomenon.

Immunoexpression of tumor suppressor genes p53, p21WAF1/CIP1 and p27KIP1 in humam astrocystic tumors

The aim of the present study was to evaluate the tumor suppressor genes p53, p21 WAF1/CIP1 and p27 KIP1 expression in astrocytic tumors, correlating the findings with the histopathological grade (WHO). An immunohistochemical study of the p53, p21 and p27 proteins using the streptavidin-biotin-peroxidase method was performed in fifty-five astrocytomas (13 grade I, 14 grade II, 7 grade III and 21 grade IV) and five samples of non-tumor brain tissue (negative control). p53 positive indices (PI) and labeling indices (LI) showed tendency to increase according to malignant progression. The nuclear expression of p27 presented similar inclination, except for the PI reduction verified in grade IV tumors. Otherwise, the cytoplasmic p27 staining was more evident between high-grade tumors (III and IV). p53 and nuclear p27 expression was correlated with the histological classification (p<0.01; test H). On the other hand, p21 indices revealed a propensity to reduction in agreement with malignant evolution of the astrocytic tumors, except for high scores observed in grade IV tumors. The non-tumor samples did not show any expression of these proteins. These results indicated the p53 mutation as an initial, relevant and potentially predictor of tumor progression event in astrocytomas, with the detection of p21 protein as an important resource for the deduction of functional situation of this gene. Moreover, the activation of p27 KIP1 was preserved in the astrocytic tumors and its cytoplasmic manifestation seems to be resultant of its nuclear expression, not demonstrating a direct impact in astrocytomas tumorigenesis.

Avaliação metabólica das lesões de isquemia e reperfusão cerebrais após oclusão bilateral das artérias carótidas comuns: estudo experimental em ratos

OBJETIVO: Caracterizar as alteracoes no metabolismo energetico apos isquemia/reperfusao cerebral atraves de um modelo experimental de isquemia global reversivel por simples oclusao das arterias carotidas comuns (ACCs) em ratos da linhagem Wistar. METODOS: Quarenta e oito ratos Wistar machos foram distribuidos aleatoriamente em dois grupos (C - Controle; T - Teste) e cada um deles redistribuidos em quatro tempos de estudos. Apos oclusao bilateral das ACCs por 30min, permitiu-se reperfusao aos animais do grupo T nos tempos 0, 5, 10 e 15min. Foram coletadas amostras de tecido cerebral e sangue arterial sistemico e quantificados os metabolitos D-glicose (GLI), piruvato (PRV), lactato (LCT) e adenosina trifosfato (ATP). RESULTADOS: Observou-se aumento nos niveis sanguineos de GLI e PRV de, respectivamente, 85,00% (p<0,05) e 51,72% (p<0,01) aos 5min de reperfusao, refletindo uma resposta sistemica a lesao isquemica cerebral. O LCT cerebral manteve-se estavel, apesar da reducao de 52,66% (p<0,05) na concentracao sanguinea aos 15min de reperfusao. As concentracoes cerebrais de ATP cairam 85,40% (p<0,05) apos isquemia, seguindo-se aumento de 3.033,40% (p<0,05) aos 5min de reperfusao, evidenciando a retomada da respiracao celular via cadeia fosforilativa. CONCLUSOES: O modelo experimental proposto produziu isquemia global transitoria parcial, com repercussao sistemica. As maiores alteracoes metabolicas foram verificadas apos os primeiros minutos de reperfusao, tipificando a lesao de reperfusao. Tais constatacoes mostram sua utilidade como ferramenta no estudo da fisiopatologia e de recursos terapeuticos da doenca cerebrovascular isquemica.

Polymorphisms of folate pathway enzymes (methylenetetrahydrofolate reductase and thymidylate synthase) and their relationship with thymidylate synthase expression in human astrocytic tumors.

Two important polymorphisms of folate cycle enzymes, methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) enhancer region (TSER) 28-bp tandem repeat, are related to risk of various types of cancer, including brain tumors, although there are few studies on this subject. A case-control study of these two polymorphisms in astrocytomas of different grades was carried out using polymerase chain reaction-restriction fragment length polymorphism, also determining the immunohistochemical expression of TS. The MTHFR 677 TT genotype was less associated with astrocytic tumors (odds ratio [OR]=0.00; p=0.0238), but the TSER polymorphism did not show any significant association. Combined genotype TT-double repeats/triple repeats (2R/3R) had a protective effect against astrocytomas (OR=0.00; p=0.0388). Expression of TS protein was observed in the majority of cases, with grade IV tumors being the exception. Moreover, the median H-score for the pilocytic astrocytomas was significantly higher when compared with that for diffuse tumors. There was an inverse correlation between the 2R/2R genotype and the highest TS-expressing tumors, and 3R/3R was relatively more frequent among the tumors grouped in the third and fourth quartiles. Our results provide support for the role of MTHFR and TS polymorphism in gliomagenesis, possibly because of the alteration of DNA methylation and repair status. Moreover, high levels of TS expression were detected in these tumors.