Visual attention in children with migraine: a controlled comparative study

The aim of this study was to evaluate the visual attention of children with migraine and compare it with a control group. Thirty migrainous children and 30 controls without headache were subjected to a visual attention assessment with Trail Making Tests (TMT) A/B, Letter Cancellation Test, and the Brazilian computerized test Visual Attention Test, third edition. The migraine group was evaluated after 2 days without headache. The migraine group had an inferior performance compared with the control group on TMT A ( P  = 0.03) and B ( P  = 0.001), and more errors on tasks 1 ( P  = 0.032) and 2 ( P  = 0.015) of the Visual Attention Test, presenting difficulty with selective and alternate attention. Attention is a neurological function that depends on structures such as the brainstem, cerebral cortex and the limbic system and on neurotransmitters such as dopamine and noradrenaline. The neurochemical aspects involved in the physiopathology of migraine and attention mechanisms probably predispose these children to visual attention deficits.     

Metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) by human cytochrome P4501B1

Cytochrome P4501B1 (CYP1B1) is the most recently identified member of the dioxin-inducible CYP1 family. CYP1B1 is constitutively expressed in most human tissues, including colon and breast, and can activate numerous chemically diverse carcinogens. We evaluated the metabolism of the dietary heterocyclic amine carcinogen 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine (PhIP) by microsomes from yeast expressing the human CYP1B1 protein. PhIP metabolites were analysed by HPLC with fluorescence and absorbance detection. We found that human CYP1B1 metabolizes PhIP to three products: N2-OH-PhIP, a mutagenic activation product; 4'-OH-PhIP, a detoxification product; and 2-OH-PhIP, the mutagenic potential of which is unknown. Metabolite identity was confirmed by co-elution with authentic standards and synchronous fluorescence spectroscopy. The identity of the 2-OH-PhIP standard was additionally confirmed by mass spectrometry. Kinetic studies of the formation of N2-OH-PhIP, 4'-OH-PhIP and 2-OH-PhIP by CYP1B1 indicated apparent Km values of 5.7 +/- 1.3, 2.2 +/- 0.5 and 1.3 +/- 0.2 microM, respectively. Apparent turnover rates were 0.40 +/- 0.03, 0.93 +/- 0.02 and 0.04 +/- 0.00 nmol product/min nmol P450, respectively. At saturating levels of substrate, CYP1B1-mediated formation of the non- mutagenic metabolite 4'-OH-PhIP was favored two-fold over that of the mutagenic metabolite, N2-OH-PhIP and >10-fold over that of 2-OH-PhIP. The formation of N2-OH-PhIP, a potent mutagen implicated in the etiology of human colon and breast cancer, indicates that CYP1B1 may play an important role in PhIP-mediated carcinogenesis.      

Exposure to 60 Hz magnetic fields and risk of lymphoma in PIM transgenic and TSG-p53 (p53 knockout) mice

The results of a number of epidemiology studies suggest that exposure to power frequency (50 and 60 Hz) magnetic fields may be a risk factor for hematopoietic neoplasia. To generate experimental data to test this hypothesis, the influence of magnetic field exposure on lymphoma induction was determined in two strains of mice that are genetically predisposed to the disease. PIM mice, which carry the pim-1 oncogene, are highly sensitive to lymphoma induction by N-ethyl-N-nitrosourea (ENU); ENU-treated PIM mice were studied as a 'high incidence' lymphoma model. TSG-p53 (p53 knockout) mice, in which the p53 tumor suppressor gene has been deleted from the germ line, develop lymphoma as an age- related change; hemizygous TSG-p53 mice were studied as a 'low incidence' lymphoma model. Beginning 1 day after a single i.p. injection of 25 mg ENU/kg body wt, groups of 30 PIM mice/sex were exposed for 18.5 h/day to pure, linearly polarized, transient-free 60 Hz magnetic fields at field strengths of 0 (sham control), 0.02, 2.0 or 10.0 Gauss (G). An additional group of 30 PIM mice/sex was exposed intermittently (1 h on, 1 h off) to 10.0 G fields. Groups of 30 TSG-p53 mice/sex were exposed continuously to magnetic field strengths of 0 (sham control) or 10.0 G; TSG-p53 mice received no ENU. Studies were terminated after 23 weeks of magnetic field exposure. Lymphoma incidence in male PIM mice exposed continuously to 10.0 G magnetic fields was significantly reduced from that seen in sex-matched sham controls; survival, lymphoma incidence and lymphoma latency in other groups of PIM mice did not differ from sham controls. Survival and lymphoma incidence in all groups of TSG-p53 mice was 7% or less, regardless of magnetic field exposure regimen. These data do not support the hypothesis that exposure to magnetic fields is a significant risk factor for lymphoid neoplasia in mice with a genetic predisposition to the disease.      

Deletion/insertion mutation that causes biotinidase deficiency may result from the formation of a quasipalindromic structure

Biotinidase is responsible for recycling the vitamin biotin from biocytin that is formed after the proteolytic degradation of the biotin- dependent carboxylases. We have identified a deletion/insertion mutation within exon D of the human biotinidase gene in a child with biotinidase deficiency. The mutation causes a frame shift and premature termination which are predicted to result in a truncated protein. We propose that the mutation occurred during DNA replication by either of two mechanisms. Both mechanisms involve formation of a quasipalindromic hairpin loop in the template and dissociation of DNA polymerase alpha. This mutation supports the formation of palindromic structures as a possible cause of deletions in eukaryotes, and supports the proposal, derived from in vitro studies, that polymerase alpha may preferentially arrest or dissociate at specific template sequences.      

In vivo hematologic effects of recombinant interleukin-6 on hematopoiesis and circulating numbers of RBCs and WBCs

Interleukin-6 (IL-6) administered as a single intravenous (IV) injection caused the following changes in the peripheral circulation of rats: (a) a biphasic neutrophilia with an initial peak at 1.5 hours and a second sustained wave of neutrophilia between four and 12 hours, (b) a mild lymphocytosis at 0.5 hours and a mild lymphopenia between 1.5 and four hours, and (c) a reticulocytosis between 12 and 24 hours. The bone marrow showed no significant changes at 1.5 hours, suggesting that the peripheral neutrophilia at that time is caused by demargination of intravascular neutrophils and not by release of marrow neutrophils. The bone marrow at 12 hours showed a mild left-shifted myeloid hyperplasia of myeloblasts and promyelocytes and a tremendous erythroid hyperplasia of intermediate and late normoblasts. The bone marrow at 24 hours showed a continued mild myeloid hyperplasia and striking erythroid hyperplasia. In conclusion, IL-6 in vivo acts as a stimulus for myelopoiesis and erythropoiesis and causes accompanying peripheral changes in the number of neutrophils, lymphocytes, and RBCs.     

Comparison of phaconit rollable IOL with acrylic foldable IOL

Background: Phaconit or ultra micro incision phacoemulsification cataract surgery involves phacoemulsification through a 0.9 millimetre sleeveless phaco tip and irrigating chopper followed by implantation of a rollable intraocular lens. The procedure leads to negligible astigmatism and faster visual recovery as compared to phacoemulsification with a foldable intraocular lens.     

Preoperative embolization of hypervascular head and neck tumours

The embolization of vascular tumours of the head and neck has become an important adjunct to the surgical treatment of these tumours. A vascular tumour in the head and neck region in a surgically treatable patient may be a candidate for embolization. Palliative embolization may be the sole treatment for high risk patients. Reducing intraoperative bleeding may shorten surgery time thus decreasing morbidity and mortality. The purpose of this study is to assess the efficacy of embolization as an adjunct to surgery or as a curative measure in the management of hypervascular head and neck tumours. We retrospectively reviewed the records of 46 consecutive patients (27 men and 16 women; mean age, 37.8 years) with 48 hypervascular head and neck tumours that had undergone preoperative transarterial, direct puncture or combined mode of embolization. Diagnosis of tumours was made on the basis of findings of imaging studies. The 46 patients underwent embolization either through transarterial route, by direct puncture technique or both direct puncture and arterial route. The devascularization reached 90–95% with the use of NBCA. The amount of devascularization reached by transarterial particle embolization is a little lesser. One patient (carotid body tumour) developed mild unilateral seventh, ninth and 10th cranial nerve palsy after transarterial embolization, transient hemiparesis was seen in another patient (nasopharyngeal angiofibroma). Both patients improved completely with steroids and had no deficit on follow up. One patient developed delayed glue migration into the middle cerebral artery territory 6 h after the procedure with no reported increase in size of the lesion in the following 5 years. Preoperative embolization of hypervascular tumour of head and neck region appears to be safe and improves the chance of complete removal during surgery with minimal blood loss.