Magnetic resonance imaging: absence of in vitro cytogenetic damage

Human lymphocytes and Chinese hamster ovary (CHO) cells in culture were exposed for 12 1/2 hours to a magnetic resonance imaging apparatus with a 2.35-Tesla magnet and 100-MHz radio frequency emission. The cells were examined for cytogenetic damage manifested either as chromosome aberrations or sister chromatid exchanges (SCEs), which constitute very sensitive measures of genetic and cellular damage. In either unstimulated or stimulated human lymphocytes, as well as in exponentially growing CHO cells, no increase in either chromosome aberrations or SCEs was found as a result of exposure to these MR conditions. The data indicate that long-term exposure to MR imaging conditions far exceeding those to be found in the clinical situation does not cause cytogenetic damage.     

咪苯嗪酮对TXA2和HHT生成的选择性抑制作用

咪苯嗪酮(CI-914)能抑制大鼠血小板环氧酶和TXA₂合成酶产物HHT的生成,而对脂氧酶产物12-HETE的生成仅高浓度药物才有弱的抑制作用,提示CI-914主要影响花生四烯酸(AA)环氧酶途径,而对脂氧酶途径影响较少。在大鼠血小板和中性白细胞CI-914能抑制TXA₂的生成,同时CI-914还可使白细胞6-keto-PGF_1a和血小板PGE₂的产生量显著增加,提示CI-914在这两种细胞引起了AA的转向合成。上述结果基本证实,CI-914在大鼠中性白细胞和血小板对TXA₂合成酶具有选择性抑制作用。     

Cerebrospinal fluid analyses in migraine patients and controls

To investigate the role of central neurotransmitters in the pathogenesis of migraine, we measured cerebrospinal fluid (CSF) levels of certain amino acids (glycine, taurine, glutamine) and metabolites of biogenic amines (5-hydroxyindoleacetic acid and homovanillic acid) in 38 migraine patients and compared them with the levels from 10 headache-free controls. The levels of taurine, glycine and glutamine were significantly higher in the migraine patients (p < 0.0001 for taurine and glycine; p < 0.0009 for glutamine); there were no significant differences among the three migraine subgroups (infrequent migraine, frequent migraine and transformed migraine). In seven patients subsequently treated with divalproex sodium, CSF taurine levels decreased significantly from pretreatment baseline values. These data support the concept that migraine is at least in part a disorder of central neurotransmission.     

Temporomandibular joint arthrography: comparison of morbidity with ionic and low osmolality contrast media

We compared patient morbidity associated with temporomandibular joint (TMJ) arthrography using both meglumine/sodium diatrizoate (60%) and the new monoacidic dimer, Hexabrix, in a double-blind randomized clinical trial in 31 patients. Patients experienced maximal discomfort from TMJ arthrography with the initial joint filling and joint distension; this rapidly resolved over 10 minutes. Delayed exacerbation of pain is less than described for shoulder arthrography. The newer contrast media promise to decrease patient morbidity with arthrography.     

CD4(+) and CD8(+) cells are key participants in the development of recurrent herpetic stromal keratitis in mice

Ocular herpes simplex virus (HSV) infection results in an immune-mediated inflammation of the corneal stroma known as herpetic stromal keratitis (HSK). Recurrent HSK is a common cause of virus-induced corneal blindness in humans. The role of CD4(+) and CD8(+) T cell subsets in the disease pathogenesis is ill defined and varies with the virus strain and host genetic background. To examine the contribution of T cell subsets to corneal disease, we studied the development of recurrent HSK in CD4 or CD8 gene knockout (KO) mice ocularly infected with HSV-1 McKrae strain. Following UV-B induced viral reactivation, corneal opacity in latently infected BALB/c (HSV sensitive) CD4 and CD8 KO mice was reduced compared to infected BALB/c mice with normal genotype. In contrast, opacity in C57BL/6 (HSV resistant) CD4 and CD8 KO latent mice did not differ from genetically normal latent mice. Virus-induced corneal opacity was not demonstrable in C57BL/6 CD4/CD8 double KO mice. Increased viral shedding, measured by reactivation rate, days shedding or viral titers, occurred in CD4 KO mice of both strains. Our findings indicate that both CD4(+) and CD8(+) cells play a role in the immunopathogenesis of recurrent HSK, and their role is dependent upon the host genetic profile.