Regulation of NO-dependent cyclic GMP formation by inflammatory agents in neural cells

In the CNS, NO is an important physiological messenger involved in the modulation of brain development, synaptic plasticity, neuroendocrine secretion, sensory processing, and cerebral blood flow [Annu. Rev. Physiol. 57 (1995) 683]. These NO actions are largely mediated by cyclic GMP (cGMP) formed by stimulation of soluble guanylyl cyclase (sGC). NO has also been recognized as a neuropathological agent in conditions such as epilepsy, stroke and neurodegenerative disorders. In these conditions, NO may contribute to excitotoxic cell death and neuroinflammatory cell damage [Brain Res. Bull. 41 (1996) 131; Glia 29 (2000) 1]. NO can be formed in every type of CNS parenchymal cell, however, cGMP appears to be formed mainly in neurons and astroglia [Annu. Rev. Physiol. 57 (1995) 683]. There is a large body of information about the regulation of NO formation in brain cells under both normal and pathological conditions but much less is known about the control of cGMP generation, in particular during neuroinflammation when there is a high NO output. Here we briefly review our present knowledge on the regulation of NO-dependent cGMP formation in brain cells under inflammatory conditions.     

Dose-time relationships in fractionated radiotherapy for cancer

The irradiation time and the dose per fraction are two key parameters in the fractionated therapy of patients with cancer. Reduction of the total treatment time and the use of low doses per fraction lead to improvements in the therapeutic relationship in cancer of the head and neck and at other tumour localisations of epithelial origin. The introduction of the linear-quadratic model and the biologically effective dose concept into the clinical setting has enabled quantitative analysis of the biological effects of radiation on malignant tumours and on acutely and slowly responding tissues, notably enhancing the perception of relationships between basic phenomena and clinical data. As a result, new and better irradiation regimens have been developed for the treatment of patients with specific tumours.     

Audiogenic seizure susceptibility in thyroid hormone receptor beta-deficient mice

As early-onset hypothyroidism produces audiogenic seizure susceptibility (AGS) in rodents, the role of TR alpha 1 and TR beta thyroid hormone receptors in AGS was investigated. AGS occurs in mice lacking specifically TR beta (Thrb(tm1/tm1)) and is marked by early onset and persistence, thereby differing from mouse strains where AGS is age-restricted. Thrb(tm1/tm1) mice display AGS whether on a mixed 129/Sv x C57BL/6J or congenic C57BL/6J background. 27% of wild-type mice on the mixed and 0% on the congenic background exhibited AGS. The inability of Thrb(tm1/tm1) mice to downregulate the response to sustained acoustic stimulation may reside in the brain or in the auditory system itself as Thrb(tm1/tm1) mice also display auditory deficits. The AGS phenotype identifies a novel neurological role for TR beta.     

Gamma-knife radiosurgery for trigeminal neuralgia

Gamma knife was installed at the PD Hinduja National Hospital and Medical Research Centre, Mumbai, India, in January 1997. In the first year of gamma-knife radiosurgery to January 1998, we treated 110 patients, of whom six had medically refractory trigeminal neuralgia. Seven treatments were administered to this group of six patients (one had bilateral neuralgia). This report evaluates the effectiveness of radiosurgery treatment in these patients. The median age of the patients was 56 years and there were five males and one female. Following Leksell stereotactic frame fixation, a magnetic resonance imaging scan was done in all. The Leksell gamma plan was used for planning. A radiosurgery dose of 70–80 Gy was delivered to the trigeminal root entry zone, 2–4 mm anterior to the junction of the pons and trigeminal nerve with a single 4 mm collimator helmet. Complete pain relief was achieved in four patients. Two had partial relief. No patient developed any radiosurgery related morbidity during the follow-up period of 5–16 months. Radiosurgery seems to be an effective approach for medically or surgically refractory trigeminal neuralgia.     

Hypoaldosteronism in three sibs due to 18-dehydrogenase deficiency

Three sibs all presented in the early neonatal period with a salt-losing syndrome. The salt-losing form of congenital adrenal hyperplasia was diagnosed and appropriate treatment with glucocorticosteroids, mineralocorticosteroids, and additional dietary salt started. Although early life was maintained with difficulty, with age all 3 children required decreasing amounts of replacement steroids to maintain normal plasma electrolyte balance. They were reinvestigated at the ages of 15 years and 8 years (twins), when cortisol synthesis and metabolism proved normal, but aldosterone synthesis was blocked by deficiency of 18-dehydrogenase. Rational treatment of these cases of a salt-losing syndrome in which aldosterone synthesis alone is blocked due to lack of the enzyme 18-dehydrogenase requires the administration of a mineralocorticosteroid drug only. Since deoxycorticosterone (acetate or pivalate) requires intramuscular administration, as life-long therapy oral fludrocortisone is preferable. Although fludrocortisone has glucocorticoid activity, the "hydrocortisone equivalent" effect of the small dosage used was unlikely to inhibit either pituitary corticotrophin or growth hormone production.     

Monoclonal antibody F1 binds to the kringle domain of factor XII and induces enhanced susceptibility for cleavage by kallikrein

In a previous study we have shown that monoclonal antibody F1 (MoAb F1), directed against an epitope on the heavy chain of factor XII distinct from the binding site for anionic surfaces, is able to activate factor XII in plasma (Nuijens JH, et al: J Biol Chem 264; 12941, 1989). Here, we studied in detail the mechanism underlying the activation of factor XII by MoAb F1 using purified proteins. Formation of factor XIIa was assessed by measuring its amidolytic activity towards the chromogenic substrate H-D-Pro-Phe-Arg-pNA (S-2302) in the presence of soybean trypsin inhibitor and by assessing cleavage on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Upon incubation with MoAb F1 alone, factor XII was auto-activated in a time-dependent fashion, activation being maximal after 30 hours. Factor XII incubated in the absence of MoAb F1 was hardly activated by kallikrein, whereas in the presence of MoAb F1, but not in that of a control MoAb, the rate of factor XII activation by kallikrein was promoted at least 60-fold. Maximal activation of factor XII with kallikrein in the presence of MoAb F1 was reached within 1 hour. This effect of kallikrein on the cleavage of factor XII bound to MoAb F1 was specific because the fibrinolytic enzymes plasmin, urokinase, and tissue-type plasminogen activator could not substitute for kallikrein. Also, trypsin could easily activate factor XII, but in contrast to kallikrein, this activation was independent of MoAb F1. SDS-PAGE analysis showed that the appearance of amidolytic activity correlated well with cleavage of factor XII. MoAb F1-induced activation of factor XII in this purified system was not dependent on the presence of high- molecular-weight kininogen (HK), in contrast to the activation of the contact system in plasma by MoAb F1. Experiments with deletion mutants revealed that the epitopic region for MoAb F1 on factor XII is located on the kringle domain. Thus, this study shows that binding of ligands to the kringle domain, which does not contribute to the proposed binding site for negatively charged surfaces, may induce activation of factor XII. Therefore, these findings point to the existence of multiple mechanisms of activation of factor XII.     

开道散合扶正和胃合剂治疗上消化道癌性狭窄疗效观察

目的：观察开道散合扶正和胃合剂治疗上消化道癌性狭窄的临床疗效。方法：对40例患者采用口服开道散、扶正和胃合剂联合胃镜下癌灶内注射5-氟脲嘧啶注射液及鸦胆子乳剂方法治疗上消化道癌性狭窄。结果：治疗后无瘤灶消失病例,34例患者肿瘤缩小达50％以上,完全缓解0例,部分缓解34例,稳定4例,进展2例,有效率为85．0％。治疗后患者吞咽困难有了较明显的改善,显效7例,有效31例,无效2例,总有效率95．0％。治疗后所有患者的卡氏评分均有所升高,与治疗前比较,差异有显著性意义（P〈0．05）,提示治疗后患者的生活质量有所改善。结论：开道散合扶正和胃合剂治疗上消化道癌性狭窄疗效满意,能使实体瘤缩小、吞咽困难改善、生活质量提高。     

Reliability of clinical guidelines in the detection of patients at risk following mild head injury: results of a prospective study

OBJECT: The aims of this study were to analyze the relevance of risk factors in mild head injury (MHI) by studying the possibility of establishing prediction models based on these factors and to evaluate the reliability of the clinical guidelines proposed for the management of MHI. METHODS: A series of 1101 patients with MHI were prospectively enrolled in this study. In all cases clinical data were collected and a computerized tomography (CT) scan was obtained. The relationship between clinical findings and the presence of intracranial lesions was studied to establish prediction models based on logistic regression and recursive partitioning analysis. Recently proposed guidelines and recommendations for the treatment of MHI were selected, calculating their diagnostic efficiency when applying each of them to our series. The incidence of acute intracranial lesions was 7.5% (83 patients). A Glasgow Coma Scale score of 14, loss of consciousness, vomiting, headache, signs of basilar skull fracture, neurological deficit, coagulopathies, hydrocephalus treated with shunt insertion, associated extracranial lesions, and patient age greater than 65 years were identified as independent risk factors. Prediction models built on clinical variables were able to indicate patients with clinically important lesions, but failed to achieve 100% sensitivity in the detection of all patients with CT scans positive for intracranial lesions within reasonable specificity limits. CONCLUSIONS: Clinical variables are insufficient to predict all cases of intracranial lesions following MHI, although they can be used to detect patients with relevant injuries. Avoiding systematic CT scan indication implies a rate of misdiagnosis that should be known and assumed when planning treatment in these patients by using guidelines based on clinical parameters.