Parotid masses: MR imaging

Over a 2-year period 20 patients who presented with masses in the parotid gland were evaluated with magnetic resonance (MR) imaging. T1-weighted images were obtained on a high-resolution, thin-section MR imaging system. When "cystic-appearing" lesions were found, T2-weighted images were obtained in order to better characterize the tumor. As in other areas of the body, MR images of parotid tumors are not usually histologically specific. MR findings may be distinctive in rare cases and define the internal architecture of complex parotid masses. Although poor tumor margination was a clue to malignancy, this was not a consistent finding. The real advantage of MR imaging in evaluating parotid masses was its ability to accurately reveal the extraparotid or intraparotid location of a tumor and demonstrate the relationship of the tumor to the facial nerve. Small and medium-sized mass lesions could be seen as superficial or deep to the facial nerve. Larger masses producing some distortion of the normal course of the nerve made identification of the nerve more difficult, if not impossible. In malignant tumors with gross invasion of the facial canal, MR images can show the extent of nerve involvement.     

去甲肾上腺素能系统对埃必定镇痛作用的影响

在大鼠电刺激甩尾测痛模型上,sc或icv埃必定(ipalbidine,Ipa)均具有剂量依赖性的镇痛作用,而脊髓蛛网膜下腔注射Ipa人产生镇痛作用;预先给予利血平可以取消scIpa的镇痛作用,这一作用可被icv补充NE所翻转;电解损毁大鼠叹侧蓝斑,ip二乙基二硫代氨基甲酸钠200mg·kg^-1,酚妥拉明ip10mg·kg^-1或icv150μg和sc哌唑嗪5mg·kg^-1均能使Ipa的镇痛作用明显减弱或消失,而sc育亨宾5mg·kg^-1和ip普萘洛尔10mg·kg^-1对Ipa的镇痛作用无明显影响。上述结果提示Ipa在中枢有镇痛作用,其部位主要在脊髓以上的神经结构,Ipa的镇痛作用可能与去甲肾上腺素能系统的a₁受体有关,而与a₂和β受体无明显关系。     

Interactions of infectious symptoms and modifiable risk factors in sudden infant death syndrome. The Nordic Epidemiological SIDS study

The aim of the study was to investigate the effect of infection on sudden infant death syndrome (SIDS) and to analyse whether modifiable risk factors of SIDS, prone sleeping, covered head and smoking act as effect modifiers. In a consecutive multicentre case-control study of SIDS in Denmark, Norway and Sweden, questionnaires on potential risk factors for SIDS were completed by parents of SIDS victims, and for at least two controls matched for gender, age and place of birth. All SIDS cases were verified by an autopsy. The study comprised 244 SIDS cases and 869 controls, analysed by conditional logistic regression. Significantly more cases than controls presenting symptoms of infectious diseases during the last week and/or last day were treated with antibiotics and had been seen by a physician. The finding is consistent with the hypothesis of an infectious mechanism in SIDS induced by local microorganism growth and toxin or cytokine production, and also adds further support to a possible association between infection and SIDS by loss of protective mechanisms, such as arousal. The risk of SIDS among infants with the combined presence of infectious symptoms and either of the other modifiable risk factors, prone sleeping, head covered or parental smoking, was far greater than the sum of each individual factor. These risk factors thus modify the dangerousness of infection in infancy.     

Analysis of tissue-specific lacZ mutations induced by N- nitrosodibenzylamine in transgenic mice

N-Nitrosodibenzylamine (NDBzA) is a contaminant found frequently in rubber baby bottle nipples and pacifiers. To evaluate more fully the mutagenic potential and analyse the molecular nature of possible mutations induced in vivo, we have studied the mutagenicity of NDBzA in vivo using the MutaMouse system. NDBzA, suspended in olive oil, was administered orally once to male mice at different doses (0, 30, 100, 425 and 750 mg/kg) and the mice were killed 30 and 90 days after treatment. As a positive control, and to compare relative mutagenicity, N-nitrosodimethylamine (NDMA) was also administered to animals in the same experiment at doses of 0, 2, 6 and 10 mg/kg. Mutant frequencies were increased in both 30 and 90 day liver samples, but not in bone marrow, after both NDBzA and NDMA treatment. However, NDBzA was >100 times less mutagenic than NDMA. A total of 81 mutants obtained from liver samples of treated animals (750 mg/kg) were characterized by DNA sequencing. While spontaneous mutations in transgenic mice have been characterized previously by a preponderance of G:C-->A:T transitions, mainly at 5'-CpG-3' dinucleotide sites, the predominant type of NDBzA- induced mutation in this study was transversion, mainly G:C-->T:A changes. The molecular characteristics of mutations induced by NDBzA indicate that they may arise from specific unidentified DNA adducts and benzylation appears to be the primary mechanism involved in formation of these DNA adducts.      

新染料四碘酚磺酞测定胺类药物的研究

本文用新酸性染料四碘酚磺酞测定了五种不同分配率的胺类药物,对影响生成酸性染料—胺配合物的主要因素,如萃取介质pH的影响、试剂用量和试剂空白值降低等进行了研究。用该法测定了五种胺类药物的线性关系、检测灵敏度和方法精密度。本法操作简便,与常用酸性染料溴甲酚紫、溴酚蓝相比,对极性较强的胺类药物如阿托品和分子量较小的胺如二乙胺基乙醇的检测灵敏度,分别提高为1.5倍和9.2倍,方法精密度,CV%<4。     

Prevalence and clinical relevance of the morphological substrate of ventricular arrhythmias in patients without known cardiac conditions detected by cardiovascular MR

Objective

Cardiac MR (CMR) identifies the substrate of ventricular arrhythmia (VA) in cardiomyopathies and coronary heart disease. However, little is known about the value of CMR in patients with VA without previously known cardiac disorders.

Methods

76 patients with VA (Lown ≥2) without known cardiac disease after regular diagnostic work-up were studied with CMR, and findings were correlated with electrocardiogram (ECG) and electrophysiological stimulation (EPS). Structural abnormalities matching the VA origin as defined by ECG and/or EPS, or a CMR-detected cardiac condition known to cause arrhythmia were defined as VA substrate. CMR findings were defined as clinically relevant, if resulting in a new diagnosis, change of treatment or additional diagnostic procedure.

Results

44/76 patients demonstrated pathological CMR findings. In 24/76 patients, the pathology was detected by CMR and not by echocardiography. CMR-based diagnoses of cardiac disease were established in 20/76 patients, and all were morphological substrates for VA. In seven patients, the location of the CMR finding (scar) directly matched the VA origin. CMR findings resulted in a change of treatment in 21 patients and/or additional diagnostics in 8 patients.

Conclusion

Undetected cardiac conditions are frequent causes of VA. This is the first study demonstrating the value of CMR for detection of morphological substrate and/or underlying cardiac disorders in VA patients without known cardiac disease.

Advances in knowledge

The high incidence of clinically relevant CMR findings which were not detected during initial diagnostic work-up strongly supports the use of CMR to screen VA patients for underlying heart disease.Although the value of cardiac MR (CMR) for the diagnosis of cardiac diseases such as myocarditis is undisputed, CMR is also predictive of patients at high risk for ventricular arrhythmias (VAs) with conditions such as hypertrophic cardiomyopathy (HCM) and coronary heart disease (CHD).^1–3 Recent studies have demonstrated the ability of CMR to identify the anatomical correlate of VA in those patients. This anatomical correlate has been characterized by CMR as a structural abnormality (e.g. fibrosis or peri-infarct region), which may go undetected using other non-invasive imaging modalities.^4,5 A number of studies have been undertaken, or are ongoing, to further elucidate the added value of CMR in patients with known cardiac conditions, to improve risk stratification for VA and to optimize therapy.^1,6–8 However, little is known to date regarding the added value of CMR for detection of an arrhythmogenic substrate or underlying cardiac condition in patients who present with VAs without known cardiac disease.Thus, the purpose of this study was to investigate the added value of CMR in patients with VAs for detection of underlying heart disease and an arrhythmogenic morphological substrate, and also to investigate the clinical relevance of CMR in those patients with positive findings.     

Abnormal assembly of membrane proteins in erythroid progenitors of patients with beta-thalassemia major

The life threatening anemia in beta-thalassemia major (Cooley's anemia) is characterized by profound intramedullary lysis, the cause of which is incompletely understood. Using marrow obtained from beta thalassemia major patients undergoing allogeneic bone marrow transplantation in Pesaro Italy, it became possible to directly study the mechanism of the intramedullary hemolysis. Based on our previous studies, we hypothesized that the unmatched alpha globin chains would interfere with normal assembly of erythroid precursor membrane proteins. Patient and control erythroid precursors were reacted with monospecific polyclonal rabbit antibodies directed against spectrin, band 3, and band 4.1 and with a monoclonal anti-alpha globin chain antibody. Using laser confocal fluorescence microscopy, normal erythroid precursors show no alpha globin chain accumulation and exhibited uniformly smooth rim fluorescence of the three membrane proteins. In some thalassemic precursors, spectrin appeared to interact with large alpha globin accumulations, and in many of these cells the spectin appeared clumped and discontinuous. Band 4.1 interacted strongly with accumulations of alpha globin in thalassemic precursors to produce bizarrely clumped zones of abnormal band 4.1 distribution. Band 3 was incorporated smoothly into thalassemic erythroblast membranes. However, the proerythroblasts and basophilic erythroblasts were significantly deficient in band 3. Thus, accumulations of alpha globin in beta- thalassemia major colocalized with and disrupt band 4.1 and spectrin assembly into the membrane. The cause of deficient band 3 incorporation into thalassemic proerythroblast membranes remains unknown. These profound membrane alterations would likely contribute to the intramedullary lysis seen in Cooley's anemia.