C. elegans as a model organism for in vivo screening in cancer: effects of human c-Met in lung cancer affect C. elegans vulva phenotypes

Cancers typically harbour several mutant forms of key cellular genes that contribute to its complex phenotype. Our lab has previously identified gain-of-function mutations in some of the receptor tyrosine kinases such as c-Met in lung cancer. In order to investigate the mutant gene in the context of a whole organism, the current choice of in vivo model is limited to the mouse. To rapidly screen the functional aspects of mutant forms of c-Met detected in lung cancer, we used the nematode C. elegans as the model organism. Transgenic worms were generated that harbour wild type or the frequently seen mutant forms of c-Met in lung cancer (c-MetR988C and c-MetT1010I). Expression of the mutant human c-Met forms in C. elegans consistently resulted in significantly low fecundity and abnormal vulval development characterized by hyperplasia. Interestingly, exposure of c-Met mutant transgenic worms to nicotine resulted in enhanced abnormal vulval development, fecundity and locomotion. Our studies provide first evidence that human c-Met mutations can be studied in C. elegans, and that carcinogens can enhance mutant c-Met function expressed in C. elegans transgenic animals. We therefore propose the use of C. elegans as a model to rapidly assess the role of cancer specific gene mutations in the context of a whole organism.     

Expression of O6-methylguanine-DNA methyltransferase in childhood medulloblastoma

Medulloblastomas (MB) are the most common malignant brain tumors in childhood. Alkylator-based drugs are effective agents in the treatment of patients with MB. In several tumors, including malignant glioma, elevated O⁶-methylguanine-DNA methyltransferase (MGMT) expression levels or lack of MGMT promoter methylation have been found to be associated with resistance to alkylating chemotherapeutic agents such as temozolomide (TMZ). In this study, we examined the MGMT status of MB and central nervous system primitive neuroectodermal tumor (PNET) cells and two large sets of primary MB. In seven MB/PNET cell lines investigated, MGMT promoter methylation was detected only in D425 human MB cells as assayed by the qualitative methylation-specific PCR and the more quantitative pyrosequencing assay. In D425 human MB cells, MGMT mRNA and protein expression was clearly lower when compared with the MGMT expression in the other MB/PNET cell lines. In MB/PNET cells, sensitivity towards TMZ and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) correlated with MGMT methylation and MGMT mRNA expression. Pyrosequencing in 67 primary MB samples revealed a mean percentage of MGMT methylation of 3.7?C92% (mean: 13.25%, median: 10.67%). Percentage of MGMT methylation and MGMT mRNA expression as determined by quantitative RT-PCR correlated inversely (n = 46; Pearson correlation r ² = 0.14, P = 0.01). We then analyzed MGMT mRNA expression in a second set of 47 formalin-fixed paraffin-embedded primary MB samples from clinically well-documented patients treated within the prospective randomized multicenter trial HIT??91. No association was found between MGMT mRNA expression and progression-free or overall survival. Therefore, it is not currently recommended to use MGMT mRNA expression analysis to determine who should receive alkylating agents and who should not.     

In vitro and in silico toxicity evaluation of bioactive 4′-aminochalcone derivatives

The 4′-aminochalcones compounds are open-chain flavonoids structures which have shown a known array of pharmacological activities, such as antibacterial, antifungal, anti-inflammatory and antitumor effects. There is little toxicological information available about these compounds in the literature. Therefore, the investigation of toxic effects of three 4′-aminochalcone derivatives was performed using in silico and in vitro assays. In silico provided results that indicated the occurrence of mutagenic and genotoxic effects. In vitro tests, using Cellular Proliferation and Viability, Micronucleus, and DNA damage by Comet assay, showed that the compounds studied also present mutagenic and genotoxic effects, which confirm the result determined by the in silico analysis. The use of experimental and computational models is complementary to each other and the results determined for 4′-aminochalones suggest that the chalcones should also be carefully considered since they show some risks to cause toxic effects to human cells.     

Rare shear-type fracture of the talar head in a thirteen-year-old child — Is this a transitional fracture: A case report and review of the literature

BACKGROUNDTalar fractures are exceedingly rare in childhood. There are very few studies on the clinical aspects, the long-term outcomes and the appropriate treatment of these fractures in pediatric patients. The mechanism of trauma consists of the application of a sudden dorsiflexion force on a fully plantar-flexed foot. Traumatic mechanism, symptoms and imaging of injuries of the talar head are similar to transitional fractures that are normally described at the distal epiphysis of the tibia: the so-called transitional fracture is defined as an epiphyseal injury when the growth plate has already started to close.CASE SUMMARYA thirteen-year-old girl reported a high-energy trauma to her right foot, due to falling from her horse. X-rays at the Emergency Department were negative. Because of persistent pain, the patient was assessed by an orthopedic surgeon after two weeks and computed tomography scans revealed a misdiagnosed displaced shear-type fracture of the talar head. Hence, surgical open reduction and fixation with two headless screws was performed. The girl was assessed regularly, and plain films at follow-up revealed complete healing of the fracture. Within six months after surgery, the patient returned to pre-injury sport activities reporting no complications.CONCLUSIONInjuries of the talar head in childhood should be considered as transitional fractures. Open reduction with internal fixation aims to reduce malalignment and osteoarthritis. Computed tomography scans are recommended in these cases.     

Neurocutaneous melanosis

OBJECTIVE: Describe the morbidity associated with a rare disease due to an embryological defect. METHODS: Retrospective revision of medical and necropsy reports. Bibliographic research using MEDLINE, LILACS and Index Medicus databases. RESULTS: 1 year-old male patient, admitted with generalized tonic-clonic seizures, evolving to deep coma and death in a few hours. Necropsy showed diffuse leptomeningeal malignant melanoma in brain stem, cerebellum, spinal cord and temporal lobe associated with a giant melanocytic nevus and satellite lesions. CONCLUSIONS: Neurocutaneous melanosis is a rare congenital syndrome characterized by the presence of large and/or multiple melanocytic nevi and pigmented tumors of the leptomeninges. It has a poor prognosis as demonstrated by the present report. It's physiopathology is believed to be due to a migration defect of the cells arising from the primitive neural crest. In these cases, an early diagnosis may improve the survival time.     

The electroencephalogram of elderly subjects revisited

The EEGs of 98 elderly volunteers were compared with those of 84 patients with a recent cerebral infarction who had achieved a stable clinical course. All subjects were uniformly evaluated according to a special protocol. The elderly volunteers were accepted for the study if they had no history, signs or symptoms of central nervous system disease. The EEGs were found to be significantly different between the two groups of subjects in several aspects. These included not only possible abnormalities, focal or diffuse, but also some normal features, such as alpha frequency and responses to photic stimulation and to hyperventilation. Groups of these differentiating features were analyzed. Using the single variable of ER (evoked response), discrimination of 80% was achieved. The variables that distinguish the volunteers from the patients may be used in the future to determine whether they are helpful in differentiating normals from patients with conditions other than stroke.     

Effects of sildenafil on exercise capacity in hypoxic normal subjects

The phosphodiesterase-5 inhibitor sildenafil has been reported to improve hypoxic exercise capacity, but the mechanisms accounting for this observation remain incompletely understood. Sixteen healthy subjects were included in a randomized, double-blind, placebo-controlled, cross-over study on the effects of 50-mg sildenafil on echocardiographic indexes of the pulmonary circulation and on cardiopulmonary cycle exercise in normoxia, in acute normobaric hypoxia (fraction of inspired O2, 0.1), and then again after 2 weeks of acclimatization at 5000 m on Mount Chimborazo (Ecuador). In normoxia, sildenafil had no effect on maximum VO2 or O2 saturation. In acute hypoxia, sildenafil increased maximum VO2 from 27 +/- 5 to 32 +/- 6 mL/min/kg and O2 saturation from 62% +/- 6% to 68% +/- 9%. In chronic hypoxia, sildenafil did not affect maximum VO2 or O2 saturation. Resting mean pulmonary artery pressure increased from 16 +/- 3 mmHg in normoxia to 28 +/- 5 mmHg in normobaric hypoxia and 32 +/- 6 mmHg in hypobaric hypoxia. Sildenafil decreased pulmonary vascular resistance by 30% to 50% in these different conditions. We conclude that sildenafil increases exercise capacity in acute normobaric hypoxia and that this is explained by improved arterial oxygenation, rather than by a decrease in right ventricular afterload.     

Lean Mass Loss and Altered Muscular Aerobic Capacity after Bariatric Surgery

IntroductionPatients undergoing weight loss surgery do not improve their aerobic capacity or peak oxygen uptake (VO₂peak) after bariatric surgery and some still complain about asthenia and/or breathlessness. We investigated the hypothesis that a post-surgery muscular limitation could impact the ventilatory response to exercise by evaluating the post-surgery changes in muscle mass, strength, and muscular aerobic capacity, measured by the first ventilatory threshold (VT).MethodsThirteen patients with obesity were referred to our university exercise laboratory before and 6 months after bariatric surgery and were matched by sex, age, and height to healthy subjects with normal weight. All subjects underwent a clinical examination, blood sampling, and body composition assessment by dual-energy X-ray absorptiometry, respiratory and limb muscle strength assessments, and cardiopulmonary exercise testing on a cyclo-ergometer.ResultsBariatric surgery resulted in a loss of 34% fat mass, 43% visceral adipose tissue, and 12% lean mass (LM) (p < 0.001). Absolute handgrip, quadriceps, or respiratory muscle strength remained unaffected, while quadriceps/handgrip strength relative to LM increased (p < 0.05). Absolute VO₂peak or VO₂peak/LM did not improve and the first VT was decreased after surgery (1.4 ± 0.3 vs. 1.1 ± 0.4 L min⁻¹, p < 0.05) and correlated to the exercising LM (LM legs) (R = 0.84, p < 0.001).ConclusionsAlthough bariatric surgery has numerous beneficial effects, absolute VO₂peak does not improve and the weight loss-induced LM reduction is associated to an altered muscular aerobic capacity, as reflected by an early VT triggering early exercise hyperventilation.