Cancer-promoting effect of Taiwan betel quid in hamster buccal pouch carcinogenesis

OBJECTIVE: To investigate the cancer-promoting effect of Taiwan betel quid in hamster buccal pouch carcinogenesis.
MATERIALS AND METHODS: Two hundred and fifty-two non-inbred mate adult Syrian golden hamsters were randomly divided into six groups, each containing forty-two animalS. A treatment regimen over a 14-week experimental period was employed with six animals per group being killed at seven different periods (every 2 weeks). The right buccal pouch of each animal was painted three times a week with various combinations of 7, 12-dimethylbenz[a]anthracene (DMBA), Taiwan betel quid extract, dimethyl sulfoxide (DMSO) and mineral oil.
RESULT: Both the number and size of tumors in animals concurrently treated with DMBA and betel quid were significantly higher than those in animals treated with DMBA alone in each killing period of 8, 10, 12 and 14 weekS. No visible tumors but hyperkeratosis and acanthosis were observed in pouches treated with betel quid alone for all killing periods.
CONCLUSION: Our results indicate Taiwan betel quid may be a co-carcinogen in human oral carcinogenesis, if extrapolation can be made from the current animal study.     

Activation of the hippocampal complex during tactile maze solving in congenitally blind subjects

Despite their lack of vision, congenitally blind subjects are able to build and manipulate cognitive maps for spatial navigation. It is assumed that they thereby rely more heavily on echolocation, proprioceptive signals and environmental cues such as ambient temperature and audition to compensate for their lack of vision. Little is known, however, about the neural mechanisms underlying spatial navigation in blind individuals in settings where these cues are absent. We therefore measured behavioural performance and blood oxygenation-level dependant (BOLD) responses using functional magnetic resonance imaging (fMRI) in congenitally blind and blindfolded sighted participants while they navigated through a tactile multiple T-maze. Both groups learned the maze task at a similar pace. In blind participants, tactile maze navigation was associated with increased BOLD responses in the right hippocampus and parahippocampus, occipital cortex and fusiform gyrus. Blindfolded sighted controls did not show increased BOLD responses in these areas; instead they activated the caudate nucleus and thalamus. Both groups activated the precuneus during tactile maze navigation. We conclude that cross-modal plastic processes allow for the recruitment of the hippocampal complex and visual cortex in congenital blindness.     

Variations of the arterial pattern in the upper limb revisited: a morphological and statistical study, with a review of the literature

A total of 192 embalmed cadavers were examined in order to present a detailed study of arterial variations in the upper limb and a meta-analysis of them. The variable terminology previously used was unified into a homogenous and complete classification, with 12 categories covering all the previously reported variant patterns of the arm and forearm.     

Rotated alphanumeric characters do not automatically activate frontoparietal areas subserving mental rotation

Functional neuroimaging studies have identified a set of areas in the intraparietal sulcus and dorsal precentral cortex which show a linear increase in activity with the angle of rotation across a variety of mental rotation tasks. This linear increase in activity with angular disparity suggests that these frontoparietal regions compute rotational transformations. An open question is whether rotated target stimuli automatically activate these frontoparietal regions, even if the task does not require rotational transformations. To address this question, we performed functional MRI while healthy male volunteers made two-choice reaction-time judgements on canonical or mirror images of two-dimensional alphanumeric characters presented at various angles of rotation. Participants had either to decide whether characters were normal or mirror-reversed (i.e., mental rotation) or judge whether the stimulus was a letter or a number (i.e., stimulus categorization). Reaction times and error rates linearly increased with the angle of rotation for mirror-reversed judgements but not for number-letter judgements, showing that only the mental rotation task required rotational transformations of the characters. The mental rotation task was associated with a linear increase in neuronal activity with angular disparity in a bilateral set of frontoparietal areas, comprising the rostral dorsal premotor cortex, frontal eye field, ventral and medial intraparietal sulcus. Neuronal activity in these regions was neither increased nor modulated by angular disparity during the stimulus categorization task. These results suggest that at least for alphanumerical characters, areas implicated in mental rotation will only be called into action if the task requires a rotational transformation.     

Functional MRI of cortical activations induced by transcranial magnetic stimulation (TMS).

The effects of repetitive transcranial magnetic stimulation (rTMS) on human brain activity and associated hemodynamics were investigated by blood-oxygenation-level-dependent (BOLD) MRI using echo-planar imaging at 2.0 T. Apart from bilateral activation of the auditory cortex by the audible rTMS discharges (23 bursts, 1 s duration, 10 Hz, 10-20 s interstimulus intervals), BOLD responses were restricted to cortical representations of actual finger movements performed either voluntarily or evoked by suprathreshold rTMS of the motor cortex. Neither subthreshold rTMS of the motor cortex nor suprathreshold rTMS of the lateral premotor cortex induced a detectable BOLD response. These findings suggest that neuronal depolarization as induced by rTMS modulates the spiking output of a brain area but does not automatically alter cerebral blood flow and oxygenation. The observation of BOLD MRI activations probably reflects the afferent intracortical processing of real movements.     

Ocular and orbital lesions: surface coil MR imaging

Nine lesions, four ocular (three melanomas, one hemangioma) and five orbital (two perioptic meningiomas, one hemangioma, one pseudotumor, one mucocele), were evaluated by magnetic resonance surface coil imaging at 1.5 T. Small ocular lesions with 3.9-4.5-mm-elevation were demonstrated. The use of two different pulse sequences resulted in separation of melanoma from adjacent retinal detachment. Contrast obtained between orbital lesions and the adjacent normal structures was better than that demonstrated with high-resolution computed tomography.     

Pre-marriage prevention of thalassaemia: report of a 100 000 case experience in Isfahan

Background: Iran like other middle east countries has a large number of major thalassaemics. Due to religious restrictions on abortion, the routine prevention of the birth of thalassaemic children by this means is not possible. The aim of this study is to describe an alternative means to prevent the birth of thalassaemic children.Methods: From January 1993 to January 1996, 100 000 people preparing for marriage were screened for the thalassaemia trait, using CBC and HbA₂ level measurement. High risk couples were referred for further consultation regarding the disease and the means of its prevention. The proposed actions of the couples regarding thalassaemia prevention were evaluated immediately after consultation and then re-evaluated three months later. Result: After the project had been running for three years the average of high risk couple initially deciding not to marry was 90% and no new cases of thalassemia were detected in the children of the screened population.Conclusion: Where both members of the couple were trait-positive their preferred choice was not to marry, rather than to marry and use other or no methods of preventing a thalassemia affected child being born to them. Cultural and religious ideas can affect such decisions and in some Islamic countries the establishment and use of a genetic counselling centre can help prevent most of new thalassaemia cases.