Synthesized MR images: comparison with acquired images

Synthesized and directly acquired spin-echo images were compared in order to assess the validity of magnetic resonance (MR) image synthesis as a method enabling retrospective formation of images by interactive manipulation of scan parameters. Synthetic images subjectively compared favorably in both accuracy and precision with acquired images when formed for the same values of echo (TE) and repetition times (TR) and for interpolated and extrapolated values of both TE and TR. Plots of synthetic and acquired signals within the same pixel sectors quantitatively showed comparable values for several regions of interest in the brain. Percent error and noise-normalized differences between acquired and synthetic images were tested as a quantitative measure of accuracy. Percent error was consistently less than 5% for brain parenchyma, and synthetic signals were accurate to within four times the noise level at acquisition. The apparent signal-to-noise ratio of synthetic images was comparable, superior, or inferior to similar acquired images, depending on the values of TE and TR. Total acquisition time required for synthetic formation of images for arbitrary values of TE and TR was equivalent to that of a single direct acquisition with a TR of 2,500 msec.     

Complex fractures of the clivus: diagnosis with CT and clinical outcome in 11 patients

During a 20-month period, fractures of the clivus occurring after craniocerebral trauma were diagnosed with computed tomography (CT) in 11 patients. Five patients had longitudinally oriented fractures; these were fatal in four patients due to either vertebral-basilar artery occlusion, brain stem trauma, or both. Six other patients had transversely oriented fractures that extended through the carotid canal and petrous temporal bone. While less frequently contributing directly to mortality, transverse fractures were also associated with cerebrospinal fluid leaks (two patients) and a cavernous sinus-carotid fistula (one patient). They were not as frequently associated with Horner syndrome or cranial nerve deficits as suggested in the current literature. This retrospective evaluation reveals two distinct injury patterns that demonstrate a difference in related morbidity and mortality.     

2,4-二氨基-5-取代苄基嘧啶类化合物的合成及其抑酶活性

本文设计并合成了18个在苄基上带有不同体积取代基的2,4-二氨基-5-取代苄基嘧啶类化合物。测定了这些化合物对乳酪菌二氢叶酸还原酶及对鸡肝二氢叶酸还原酶的表观50%抑制作用。其中2,4-二氨基-5-(3′-羟基-4′-甲氧基)苄基、2,4-二氨基-5-(3′-甲氧基-4′-甲氧乙氧基)苄基嘧啶对上述二氢叶酸还原酶(DHFR)的选择性较好。     

p53 and MDM2 expression in odontogenic cysts and tumours

OBJECTIVE: The aim of this report was to assess p53 and MDM2 expression in odontogenic cysts and tumours, as they are known to play important roles in cell proliferation and tumorigenesis. MATERIALS AND METHODS: The expression of p53 and MDM2 proteins was determined immunohistochemically in 51 formalin-fixed, paraffin embedded specimens of odontogenic cysts and tumours.RESULTS: No positivity to p53 was found in the cases studied. MDM2 expression in ameloblastoma was higher than in radicular cysts, but lower than that observed in odontogenic keratocysts. No difference was observed between MDM2 expression in radicular cyst and adenomatoid odontogenic tumour. The clear-cell odontogenic ameloblastoma presented strong immunoreaction to this antigen.CONCLUSIONS: The results suggest that MDM2 overexpression may be involved in the pathogenesis of some odontogenic lesions.     

Immune responses to Aspergillus antigen in IL‐4‐/‐ mice and the effect of eosinophil ablation

BACKGROUND: Exposure to Aspergillus fumigatus allergens results in enhanced total serum IgE and peripheral blood eosinophils in mice. The associated pulmonary inflammation and immunologic responses are comparable to those detected in human allergic bronchopulmonary aspergillosis. Allergen-induced cytokines are thought to regulate the inflammatory and immune responses in these animals. METHODS: In the present study, we exposed C57BL/6 and BALB/c mice to A. fumigatus antigen. Both wild-type and IL-4 knockout phenotypes of animals of both strains were used. Some animals were also treated with anti-IL-5 or anti-IFN-gamma. Total serum IgE, Aspergillus species IgG subclass, peripheral blood eosinophils, and lung histology were studied. RESULTS: The results demonstrate similar lung inflammation in all wild-type and IL-4-/- animals exposed to A. fumigatus antigen. Similarly, in spite of the diverse immune response produced by the anticytokine treatment, no major differences were detected among any of the animal groups studied. CONCLUSIONS: It can be concluded that A. fumigatus exposure in an immunologically unaltered host is predominantly of a Th2 type, and that depletion of the Th2 cytokine leads to a similar lung inflammation but with a characteristic Th1 response, suggesting that the pathogenesis of allergic aspergillosis is the result of multiple induction pathways.     

Detection of Antimicrobial Compounds by Bioautography of Different Extracts of Leaves of Selected South African Tree Species

The hexane, acetone, dichloromethane and methanol extracts of Combretum vendae A.E. van Wyk (Combretaceae), Commiphora harveyi (Engl.) Engl. (Burseraceae), Khaya anthotheca (Welm.) C.DC (Meliaceae), Kirkia wilmsii Engl. (Kirkiaceae), Loxostylis alata A. Spreng. ex Rchb. (Anacardiaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae) and Protorhus longifolia (Bernh. Ex C. Krauss) Engl. (Anacardiaceae) were screened for their antimicrobial activity. The test organisms included bacteria (Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus), and fungi (Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Microsporum canis and Sporothrix schenckii). A simple bioautographic procedure, involving spraying suspensions of the bacteria or fungi on thin layer chromatography (TLC) plates developed in solvents of varying polarities was used to detect the number of antibacterial and antifungal compounds present in the extracts. All the extracts had antimicrobial activity against at least one of the test microorganisms. This activity was denoted by white spots against a red-purple background on the TLC plates after spraying with tetrazolium violet. Twenty seven TLC plates; 9 for each solvent system and 3 different solvent systems per organism were tested in the bioautographic procedure. Of the bacteria tested, S. aureus was inhibited by the most compounds separated on the TLC plates from all the tested plants. Similarly, growth of the fungus C. neoformans was also inhibited by many compounds present in the extracts. Loxostylis alata appeared to be the plant extract with the highest number of inhibition bands when compared with other plants tested against both bacteria and fungi. This species was selected for in depth further study.     

REVIEW ARTICLE: Paediatric nasopharyngeal rhabdomyosarcoma: A case series and literature review

Rhabdomyosarcoma (RMS) is the most common soft tissue tumour in children, with the head and neck region accounting for 35–40% of cases. Nasopharyngeal RMSs tend to grow rapidly and invade adjacent structures. Both the Intergroup Rhabdomyosarcoma Studies and the European Studies have established that the ideal management of this disease is multimodal, using a combination of surgery, chemotherapy and radiotherapy. This case series examines the role of radiotherapy in the management of paediatric nasopharyngeal RMSs, with particular reference to long-term morbidity and disease-free survival. The cases of five children with nasopharyngeal RMS were reviewed and a systematic review of the literature contained in the PubMed databases was conducted to establish 24 individually detailed cases. Management in all patients was multimodal, using a combination of chemotherapy, radiotherapy as well as surgery. External beam radiotherapy is an integral component of treatment for nasopharyngeal RMSs. With more patients surviving for longer periods, more long-term sequelae of radiotherapy have been reported. Complications include sensorineural deafness, endocrine manifestations following radiation of the pituitary gland, cranial nerve palsies, second malignancies within the radiation field, cataract formation, retinopathy and growth disturbance. Morbidity from radiotherapy may be considerable and depends on the field and dose of radiation. Current advances in radiotherapy are aimed at improving the rate of tumour control and reducing such complications. Recent improvements in imaging and conformal techniques have the potential to reduce the morbidity associated with radiotherapy in this cohort.