胸腰椎骨折术后内固定松动、断裂的原因及预防

目的 探讨椎弓根螺钉系统用于胸腰椎骨折术后出现松动、断裂的原因，并提出相应的预防对策。方法 12例胸腰椎骨折术后内固定失效病例，采用RF系统3例，AF系统9例。均未行植骨融合，AF系统中未按要求安装横连结3例，术后伤椎前缘高度平均恢复至正常的85．2％。结果 术后8—21个月出现棒断裂4例，螺钉断裂3例，钉帽松动5例。结论 内固定物的自身问题、术者的经验欠缺及操作不规范是胸腰椎骨折术后椎弓根螺钉系统松动、断裂的原因，但伤椎骨结构未能得到良好重建及术后椎间盘退变可能是其更重要的因素。因此重视内固定物的选择、加强规范操作，强调对损伤椎体及椎间盘的全面处理是预防内固定失效的有效措施。     

Lenticulostriate arteries in aging process: an angiographic study

Histological studies describe in detail the changes of the small arteries wall with controversial results concerning lumen narrowing during the aging process. In this study, the anatomic and the angiographic parameters of the medial and lateral lenticulostriate arteries were analysed in 64 carotid angiograms. Only 20% of the total number of lenticulostriate arteries were shown on angiograms. Collateral branches were rarely visible, especially those of medial group. The course of the lenticulostriate arteries was mostly straight or moderately tortuous. No significant differences were noted in any of the measured parameters when compared with the age (p greater than 0.05). It appears that age-related changes spread over external layers of small arteries, with no lumen narrowing or filling defect.     

Current methods in the diagnosis of adult-age cystic fibrosis]

An 19 year old male patient with cystic fibrosis is reported. The clinical, pathogenetic, anatomical features and literature data are reviewed. Attention is called to recent diagnostic facilities.     

Urinary medium-chain acylcarnitines in medium-chain acyl-CoA dehydrogenase deficiency, medium-chain triglyceride feeding and valproic acid therapy: sensitivity and specificity of the radioisotopic exchange/high performance liquid chromatography method.

To determine the sensitivity and specificity of detecting urinary medium-chain acylcarnitines for the diagnosis of MCAD deficiency, 114 urine specimens from 75 children with metabolic diseases and controls were analyzed in a blinded fashion using a radioisotopic exchange/HPLC method. All 47 patients with MCAD deficiency were correctly diagnosed using the criterion hexanoylcarnitine or octanoylcarnitine peak areas larger than those of other medium-chain acylcarnitines. The majority of them were tested during the asymptomatic state without L-carnitine loading. Four patients with other defects of fatty acid oxidation and three patients receiving valproic acid had a similar acylcarnitine excretion pattern. To further examine the specificity of the method, eight infants receiving a diet enriched with medium-chain triglycerides and 13 additional patients receiving valproic acid were studied. Most of these also tested positive for MCAD deficiency by the above criterion. Analysis by a new gas chromatographic-mass spectrometric procedure revealed that octanoylcarnitine, not valproylcarnitine, was the most abundant medium-chain carnitine ester excreted by a patient treated with valproic acid. Quantitation of urinary hexanoylcarnitine and octanoylcarnitine showed considerable overlap among patients with MCAD deficiency and those receiving valproic acid or a medium-chain triglyceride-enriched diet. MCAD deficiency can be reliably detected in urine specimens by this method without the need for prior carnitine loading. However, other defects in fatty acid oxidation must be differentiated from MCAD deficiency, and a history of medium-chain triglyceride or valproic acid administration must be considered if the diagnosis of MCAD deficiency is sought through analysis of urinary acylcarnitines.     

Amino acid sequences and structures of chicken and turkey beta 2-microglobulin

The complete amino acid sequences of chicken and turkey beta 2-microglobulins have been determined by analyses of tryptic, V8-proteolytic and cyanogen bromide fragments, and by N-terminal sequencing. Mass spectrometric analysis of chicken beta 2-microglobulin supports the sequence-derived Mr of 11,048. The higher apparent Mr obtained for the avian beta 2-microglobulins as compared to human beta 2-microglobulin by SDS-PAGE is not understood. Chicken and turkey beta 2-microglobulin consist of 98 residues and deviate at seven positions: 60, 66, 74-76, 78 and 82. The chicken and turkey sequences are identical to human beta 2-microglobulin at 46 and 47 positions, respectively, and to bovine beta 2-microglobulin at 47 positions, i.e. there is about 47% identity between avian and mammalian beta 2-microglobulins. The known X-ray crystallographic structures of bovine beta 2-microglobulin and human HLA-A2 complex suggest that the seven chicken to turkey differences are exposed to solvent in the avian MHC class I complex. The key residues of beta 2-microglobulin involved in alpha chain contacts within the MHC class I molecule are highly conserved between chicken and man. This explains that heterologous human beta 2-microglobulin can substitute the chicken beta 2-microglobulin in exchange studies with B-F (chicken MHC class I molecule), and suggests that the MHC class I structure is conserved over long evolutionary distances.     

Doctor's delay in HIV infection caused by blood transfusion]

Transfusion-associated symptomatic HIV infection in four patients led to death in two patients and to development of serious neurological sequelae in a third patient who also transmitted HIV infection to his spouse. The tardy diagnosis of HIV-associated disease in all cases can be ascribed to ignoring the earlier blood transfusion as a possible cause of HIV infection. This was due partly to advanced age of the patients and partly to lack of familiarity of the attending physicians with HIV-associated problems. This resulted in a substantial doctor's delay.     

Renal dysfunction after myocardial revascularization.

OBJECTIVES: In this study, we evaluate the incidence of and analyse the pre and intraoperative risk factors for the development of postoperative renal dysfunction (PRD), and the impact of such an event on perioperative mortality and on hospital length of stay. In addition, we sought to investigate the influence of a mildly increased serum creatinine (1.3-2.0 mg/dl) on perioperative mortality and morbidity. METHODS: The study included 2445 consecutive patients who had no pre-existing renal disease (creatinine or=2.1 mg/dl with a preoperative-to-postoperative increase >or=0.9 mg/dl. Univariate and multivariate analyses were performed where appropriate. RESULTS: Global 30-day mortality was 0.7%. The incidence of PRD was 5.6% (136 patients). Mortality for patients who experienced PRD was 8.8 vs. 0.1% for patients who did not (P<0.001). PRD increased the length of hospital stay by 3.4 days (7.6 vs. 11.0 days; P<0.001), and patients who needed haemodialysis (11%) had a perioperative mortality of 33.3% and a mean hospital length of stay of 16 days. Multivariable logistic regression identified the following variables as independent predictors of PRD: age (P=0.017; odds ratio (OR) 1.3 per 10 years), angina class III/IV (P=0.003; OR 1.7); cardiopulmonary bypass time (P=0.007; OR 1.01 per minute); preoperative serum creatinine levels: group 1 (1.3-1.6 mg/dl (P<0.001; OR 5.5)) and group 2 (1.7-2.0 mg/dl (P<0.001; OR 14.2)). Finally, a mild elevation of the preoperative creatinine level (1.3-2.0 mg/dl) increased significantly the probability of perioperative mortality, low cardiac output, haemodialysis and prolonged hospital stay. CONCLUSIONS: Although the likelihood of PRD in patients without pre-existing renal dysfunction is relatively low, it dramatically increases mortality, morbidity and length of stay after CABG. Mildly elevated (>1.2 mg/dl) preoperative serum creatinine level significantly increases the perioperative mortality and morbidity.     

咪唑安定对低血容量休克鼠静脉血管可容性的影响

目的研究咪唑安定对低血容量休克血管可容性的影响及可能的作用机制。方法血管可容性的变化通过测量注射咪唑安定前后全身平均循环充盈压(Pmcf)来表示。实验鼠分为对照组(n=8),交感神经阻断组(SNSB,n=8),交感神经阻断 去甲肾上腺素组(SNSB NA,n=9),低血容量组(n=5)。静脉注射咪唑安定0.1、0.3、0.5、1.0mg·kg-1后2min测量Pmcf。结果与用药前相比,咪唑安定导致对照组、低血容量组、SNSB NA组平均动脉压明显下降(P<0.05),但对照组呈剂量依存性方式。对照组和低血容量组的Pmcf呈现剂量依存性下降(P<0.05),但SNSB组、SNSB NA组无改变。结论 咪唑安定可引起剂量依存性的静脉血管舒张,而这种作用主要是源于其对静脉血管交感神经张力的抑制。     

Agonist-independent activation of acetylcholine receptor channels by protein kinase A phosphorylation.

Protein phosphorylation is a ubiquitous and one of the most effective means of regulating protein activity. Receptor phosphorylation is a key event in signal transduction. The question, therefore, that arises is whether this modulatory mechanism might produce functional changes in a membrane receptor in the absence of its naturally occurring ligand. To examine this issue, single-channel properties of purified acetylcholine receptors (AChRs) from Torpedo californica reconstituted in lipid bilayers were studied in the absence of ACh in both unphosphorylated preparations and after in vitro phosphorylation by a purified catalytic subunit of cyclic AMP-dependent protein kinase (protein kinase A). Notably, the spontaneous open-channel probability of phosphorylated AChRs is significantly higher than that of unphosphorylated AChRs. Channel activation by protein kinase A is correlated with AChR phosphorylation and is abolished by alpha-bungarotoxin. Analysis of probability distributions of the open dwell times indicates that, similar to unphosphorylated AChR has two distinct open states, short- and long-lived. The frequency of occurrence of the long openings over the short and the magnitude of both time constants increase after phosphorylation, as they do with agonist concentration. Thus, phosphorylation of AChR gamma and delta subunits activates AChR channel opening in the absence of ligand binding. This result is compatible with the notion that protein phosphorylation may effectively act as an intracellular ligand with the phosphorylation sites envisioned as cytoplasmic ligand binding sites.