Poly(3-hexylthiophene) (PT6), poly(3-octylthiophene) (PT8), poly(3-decylthiophene) (PT10) and poly(3-dodecylthiophene) (PT12) were synthesized by electrochemical and chemical polymerization. Investigation of these polymers by means of gel permeation chromatography indicates that the polymers prepared from the different monomers under similar conditions do not differ substantially considering molecular weight and molecular weight distribution. Bimodal distributions were found for electropolymerized polymers, and with increasing polymerization time, the high-molecular-weight and probably highly branched fraction increased relatively to the low-molecular-weight fraction. The microstructure of the polymers was investigated by nuclear magnetic resonance, and it has been found that the polymers exhibit more types of structural units than expected from a simple coupling of adjacent thiophene moieties in 2,5′-positions. Chemical oxidation with iron trichloride in chloroform gave soluble, high-molecular-weight poly(3-alkyl-thiophene)s with a rather low amount of irregular couplings, and these more regular polymers exhibited a higher degree of crytallinity. Room temperature conductivities of the oxidized polymers were between 0,1 and 30 S/cm depending on the polymerization conditions, but these values were rather independent of the length of the alkyl substituent. 相似文献
n= 8), multidrug resistance
or noncompliance to the medical treatment (n= 11),
parenchymal sequelae (n= 3), suspected cancer
(n= 5), and for the correction of postpneumonectomy
bronchopleural fistula and empyema (n= 1). On
admission, eight patients presented with sputum positivity (28.6%).
Similar to previous series, tubercular predilection for upper lobes was
confirmed (21/28, 75%); accordingly, upper lobectomy through an
extrapleural approach was the most common procedure (16/28, 57.1%).
Atypical segmental resections or segmentectomies were performed in
seven patients (25%), whereas a bilobectomy was necessary in another
three patients (10.7%) and a completion pneumonectomy in one (3.6%).
Additional procedures were an open-window thoracostomy with
transpericardial closure of the main bronchus and a tailored
thoracoplasty. No operative mortality was reported. Healing was
achieved in 26 patients (93%). Bleeding, either from the chest wall or
hilar dissection, was the only reported intraoperative complication.
Median blood loss, inclusive of early postoperative collections from
chest tubes, reached 1330 ml (range 100–3700 ml). Major postoperative
complications included recurrent disease (2/28, 7%) in sputum-positive
patients and segmental pulmonary embolism (3.5%). Causes of minor
morbidity were air leaks resulting in residual space undergoing
spontaneous resolution (18%), wound breakdown (14%), and, fever
(11%). This limited series confirms the therapeutic value of the
surgical treatment of postprimary tuberculosis, provided that correct
indications, adequate pre- and postoperative medical coverage, and
meticulous technique are applied.相似文献
Background. We developed a method of closed-chest cardiopulmonary bypass to arrest and protect the heart with cardioplegic solution. This method was used in 54 dogs and the results were retrospectively analyzed.
Methods. Bypass cannulas were placed in the right femoral vessels. A balloon occlusion catheter was passed via the left femoral artery and positioned in the ascending aorta. A pulmonary artery vent was placed via the jugular vein. In 17 of the dogs retrograde cardioplegia was provided with a percutaneous coronary sinus catheter.
Results. Cardiopulmonary bypass time was 111 ± 27 minutes (mean ± standard deviation) and cardiac arrest time was 66 ± 21 minutes. Preoperative cardiac outputs were 2.9 ± 0.70 L/min and postoperative outputs were 2.9 ± 0.65 L/min (p = not significant). Twenty-one-French and 23F femoral arterial cannulas that allowed coaxial placement of the ascending aortic balloon catheter were tested in 3 male calves. Line pressures were higher, but not clinically limiting, with the balloon catheter placed coaxially.
Conclusions. Adequate cardiopulmonary bypass and cardioplegia can be achieved in the dog without opening the chest, facilitating less invasive cardiac operations. A human clinical trial is in progress. 相似文献
Objective. To determine in a prospective study the normal MRI morphology of the sacroiliac joints (SIJs) in relation to age and sex
during adolescence. Design and patients. A total of 98 children (63 boys, mean age 12.7±2.8 years; 35 girls, mean age 13.7±2.3 years), ranging in age from 8 to 17
years, with juvenile chronic arthritis (JCA) but without signs of sacroiliitis fulfilled the study prerequisites (no back
pain and no pathologic changes of the SIJs on physical examination before MRI in a 1.5-year follow-up). An additional eight
HLA-B27-negative boys and eight HLA-B27-negative girls without arthritis served as controls. The MRI protocol comprised a
T1-weighted SE sequence, an opposed-phase T2*-weighted GE sequence, and a dynamic contrast-enhanced study in single-section
technique. Results. Noncontrast MRI permitted differentiation of “open” from ossified segmental and lateral apophyses of the sacral wings, with
a significant difference in age (P <0.05) between children with open and ossified apophyses. Ossification of the apophyses of the sacral wings was seen significantly
earlier (P <0.05) in girls than in boys. Girls also had a significantly higher incidence of transitional lumbosacral vertebrae, pelvic
asymmetries, and accessory joints. In the contrast-enhanced opposed-phase MRI study, normal cartilage of the SIJs showed no
contrast enhancement whereas the joint capsule showed a moderate enhancement. Conclusion. There are significant age- and sex-related differences in the normal MRI morphology of juvenile SIJs. Our findings might
serve as a standard of comparison for the evaluation of pathologic changes – in particular for the early identification of
juvenile sacroiliitis. 相似文献
The present study describes cause-specific mortality of asbestos cement workers in the Emilia Romagna region of Italy. The cohort included workers in ten factories, most of which started operating between 1955 and 1965. Asbestos, mainly chrysotile, constituted 10%–20% of the dry component of the mixture. Crocidolite range between 5% and 50% of total asbestos. Asbestos concentrations up to 44 ff/cc were reported prior to 1975, while in recent years they have usually been below 0–1 ff/cc. The cohort included 3341 workers who had at some time been employed in the ten factories under study. Their mortality experience was compared with that of the population resident in Emilia Romagna. Vital status was ascertained at 1989. Seventy-three subjects were lost to followup (2.2%). Mortality from all causes and from all types of cancer was increased in the cohort. Malignant neoplasms of the respiratory tract showed a significant increase (SMR: 134; 90% confidence interval: 101–175; 40 observed) due to lung cancer (SMR: 124; 90% confidence interval: 91–166; 33 observed) and neoplasms of the pleura, mediastinum, and other parts of the respiratory tract (SMR: 602; 90% confidence interval 237–1267; 5 observed). The discrepancy between observed and expected mortality mainly concerned subjects with at least 20 years of employment in the factories. Five more cases of histologically confirmed mesothelioma occurred after the end of follow-up. 相似文献
The effects of intraventricular nerve growth factor (NGF) or saline treatments on extracellular acetylcholine (ACh), dopamine (DA) and adenosine (Ade) levels in the cortex and striatum of rats with unilateral devascularizing cortical lesions were studied in vivo with microdialysis. The devascularizing cortical lesion produced a decrease in extracellular ACh levels in both cortex and striatum as compared to those in normal rats, while the NGF treatment produced a significant increase in ACh levels in both regions. NGF could even increase cortical ACh levels in normal rats. The cortical lesion produced a decrease in extracellular DA in the cortex, while the NGF treatment appeared to reverse this effect. No significant changes in DA were observed in the striatum. The present study gives evidence that a unilateral cortical devascularizing lesion leads to changes in extracellular ACh and DA levels in cortex and striatum and that these changes could be reversed with intraventricular NGF treatment. 相似文献