Load transmission through the callus site with external fixation systems: theoretical and experimental analysis

The fracture callus contribution to the total rigidity of external fixator-fractured bone element was analysed. This study was achieved from both theoretical and experimental perspectives. The theoretical study was done using the finite element method with a three-dimensional model. In this model, both the callus and the development of its elastic characteristics were considered. A series of 38 New Zealand-California white rabbits with tibial fractures treated with some external fixation system was used in this study. Such devices could reproduce either rigid or elastic features. The frame dynamization can be obtained at different fracture healing stages. Animals were classified into four series: (1) rigid fixators, (2) dynamized fixators two weeks after surgery, (3) three weeks after surgery and (4) four weeks after surgery. Tension tests were performed to evaluate callus strength. Theoretical results showed significant levels of callus load transmission (85.5%) when the callus elastic modulus is 1/100 of the elastic modulus of intact bone in an external fixator with rigid features. Experimental analysis of the callus obtained with different external fixator systems did not show differences among them. This fact implies that the immature callus theoretically modelled (E = 100 N mm-2) appears early in the rabbit fracture model (before two weeks, when first dynamization was made), for this reason no differences were found between the two types of treatment (rigid and dynamized systems). This fact questions the reliability of the dynamization process in external fixation of fractures and it implies accurate investigations in the clinical field.     

Quantitative measurements of desmin and vimentin immunostains and cell density in leiomyomas and leiomyosarcomas

The distinction between benign and malignant smooth muscle tumours relying on histological features such as the mitotic index and pleomorphism remains a generally acknowledged difficulty in modern pathology. A cell image processor was therefore used to quantitatively assess the desmin and vimentin immunostain in 39 smooth muscle tumours which included 26 benign (leiomyomas) and 13 malignant (leiomyosarcomas) cases. The 13 leiomyosarcomas were primary (non-recurrent and non-metastatic). Ploidy level and cell density were also assessed on each of these 39 tumours by means of the computer-assisted microscopic analysis of 5-microns thick Feulgen-stained histological sections. The results show that while neither the ploidy level determination nor the quantitative assessment of the vimentin immunostain made it possible to distinguish between leiomyomas and leiomyosarcomas, cell density determination and the quantitative assessment of the desmin immunostain enabled such a distinction to be made. Indeed, the leiomyomas exhibited a much higher level of desmin positivity than the leiomyosarcomas, as did diploid tumours as compared to the aneuploid (benign or malignant) ones. Furthermore, the leiomyoma group exhibited a significantly lower mean cell density value than the leiomyosarcoma group. The present study further confirms the lack of relationship between ploidy level and cytological malignancy in smooth muscle tumours.     

Heavy metals in shrimp culture areas from the Gulf of Fonseca, Central America. II. Cultured shrimps

An increase in magnesium intake has been suggested to lower blood pressure (BP). However, the results of clinical studies are inconsistent. We studied the effects of magnesium supplementation on office, home, and ambulatory BPs in patients with essential hypertension. Sixty untreated or treated patients (34 men and 26 women, aged 33 to 74 years) with office BP >140/90 mm Hg were assigned to an 8-week magnesium supplementation period or an 8-week control period in a randomized crossover design. The subjects were given 20 mmol/d magnesium in the form of magnesium oxide during the intervention period. In the control period, office, home, and average 24-hour BPs (mean+/-SE) were 148.6+/-1.6/90.0+/-0.9, 136.4+/-1.3/86.8+/-0.9, and 133.7+/-1.3/81.0+/-0.8 mmHg, respectively. All of these BPs were significantly lower in the magnesium supplementation period than in the control period, although the differences were small (office, 3.7+/-1.3/1.7+/-0.7 mmHg; home, 2.0+/-0.8/1.4+/-0.6 mmHg; 24-hour, 2.5+/-1.0/1.4+/-0.6 mm Hg). Serum concentration and urinary excretion of magnesium increased significantly with magnesium supplementation. Changes in 24-hour systolic and diastolic BPs were correlated negatively with baseline BP or changes in serum magnesium concentration. These results indicate that magnesium supplementation lowers BP in hypertensive subjects and this effect is greater in subjects with higher BP. Our study supports the usefulness of increasing magnesium intake as a lifestyle modification in the management of hypertension, although its antihypertensive effect may be small.     

Bronchoscopy versus empirical therapy in HIV-infected patients with presumptive Pneumocystis carinii pneumonia. A decision analysis

The outcomes of alternative strategies for the management of pulmonary complications in patients infected with the human immunodeficiency virus (HIV) and with suspected Pneumocystis carinii pneumonia were compared using a decision analysis model. A decision tree was constructed using baseline probabilities derived from published data and expert opinion. The case scenario analyzed was that of a patient not currently receiving anti-Pneumocystis prophylaxis who presents with moderate pulmonary symptoms and fulfills the Centers for Disease Control (CDC) criteria for presumptive P. carinii pneumonia. Two strategies were compared: (1) early bronchoscopy with appropriate therapy based on the results, and (2) empiric treatment for P. carinii (trimethoprim/sulfamethoxazole or pentamidine, and steroids) with delayed bronchoscopy in those not responding to 5 days of empiric therapy. The expected 1-month survival rate (with and without quality of life adjustment) was found to be essentially the same for the two strategies using the baseline probabilities, and the decision remained a toss-up within the clinically relevant range of published probabilities for P. carinii pneumonia in patients fulfilling the CDC criteria. Because early bronchoscopy does not offer any additional survival benefits and is associated with greater costs and disutility, empiric therapy would appear to be the superior management strategy in this scenario.     

Popliteal venous aneurysm: report of two cases and review of the world literature

Two new cases of popliteal venous aneurysm are reported and added to the 22 other cases of popliteal venous aneurysm available for review. Both patients were first seen with acute pulmonary embolism and were treated with thrombolytic therapy followed by anticoagulation. Each had recurrent venous thromboembolism before discovery of the popliteal venous aneurysm. One popliteal venous aneurysm was diagnosed with phlebography and the second with venous duplex imaging, confirmed with phlebography. Both were surgically corrected with tangential aneurysmectomy and lateral venorrhaphy. Twenty-four cases of popliteal venous aneurysm are now available for review. Seventy-one percent (17 of 24) presented with pulmonary embolism, 88% (21 of 24) were saccular, and 96% (23 of 24) were located in the proximal popliteal vein. All but two were diagnosed by ascending phlebography. Three patients received no treatment: in two of these the outcome was not documented and the third had occasional pain. Two patients received anticoagulation without subsequent operative repair and both died of recurrent pulmonary emboli. Operative correction resulted in a 75% patency rate with 21% complications, most of which were related to postoperative anticoagulation. No patient who was operated on had subsequent pulmonary embolism, and there were no operative deaths. We suggest that all patients who have pulmonary embolism have lower-extremity venous duplex imaging. All popliteal venous aneurysms should be surgically repaired, inasmuch as nonoperative therapy results in recurrent thromboembolism and an unacceptably high mortality rate. Tangential aneurysmectomy with lateral venorrhaphy is the recommended procedure.     

Optimal method of urgent decompression of the collecting system for obstruction and infection due to ureteral calculi

PURPOSE: We compare the efficacy of percutaneous nephrostomy with retrograde ureteral catheterization for renal drainage in cases of obstruction and infection associated with ureteral calculi. MATERIALS AND METHODS: We randomized 42 consecutive patients presenting with obstructing ureteral calculi and clinical signs of infection (temperature greater than 38 C and/or white blood count greater than 17,000/mm.3) to drainage with percutaneous nephrostomy or retrograde ureteral catheterization. Preoperative patient and stone characteristics, procedural parameters, clinical outcomes and costs were assessed for each group. RESULTS: Urine cultures obtained at drainage were positive in 62.9% of percutaneous nephrostomy and 19.1% of retrograde ureteral catheterization patients. There was no significant difference in the time to treatment between the 2 groups. Procedural and fluoroscopy times were significantly shorter in the retrograde ureteral catheterization (32.7 and 5.1 minutes, respectively) compared with the percutaneous nephrostomy (49.2 and 7.7 minutes, respectively) group. One treatment failure occurred in the percutaneous nephrostomy group, which was successfully salvaged with retrograde ureteral catheterization. Time to normal temperature was 2.3 days in the percutaneous nephrostomy and 2.6 in the retrograde ureteral catheterization group, and time to normal white blood count was 2 days in the percutaneous nephrostomy and 1.7 days in the retrograde ureteral catheterization group (p not significant). Length of stay was 4.5 days in the percutaneous nephrostomy group compared with 3.2 days in the retrograde ureteral catheterization group (p not significant). Cost analysis revealed that retrograde ureteral catheterization was twice as costly as percutaneous nephrostomy. CONCLUSIONS: Retrograde ureteral catheterization and percutaneous nephrostomy effectively relieve obstruction and infection due to ureteral calculi. Neither modality demonstrated superiority in promoting a more rapid recovery after drainage. Percutaneous nephrostomy is less costly than retrograde ureteral catheterization. The decision of which mode of drainage to use may be based on logistical factors, surgeon preference and stone characteristics.     

红外光谱法研究烯烃对Ce(Ⅳ)Y分子筛脱硫效果的影响

选取1-辛烯、1,5-己二烯、环己烯等作为模拟汽油中的烯烃模型化合物,采用FT-IR方法得到饱和吸附不同模拟油之后的Ce(Ⅳ)Y分子筛的红外光谱图,根据红外光谱信息研究烯烃对Ce(Ⅳ)Y分子筛选择性吸附脱硫性能的影响。研究发现,Ce(Ⅳ)Y分子筛阳离子和烯烃的双键发生了σ-π络合,从而跟与Ce(Ⅳ)Y存在SM作用的噻吩形成了竞争吸附。在含烯烃的模拟油中,由于烯烃和分子筛发生相互作用,占据了吸附剂的活性位,导致Ce(Ⅳ)Y分子筛的脱硫性能显著降低。     

Primary malignant fibrous histiocytoma of the lung. Report of a case with bronchial brushing cytologic features

BACKGROUND: Malignant fibrous histiocytoma (MFH) arising primarily in the lungs is rare, and a preoperative diagnosis, as well as a surgical planning, is very important because of the tumor's propensity for vascular invasion and its low incidence of lymph node metastasis. The correct preoperative diagnosis of thoracic MFH is not easy to establish because the small fragments from needle and transbronchial biopsies are often inadequate for a conclusive histologic analysis. A preoperative bronchial brushing cytology suggestion of the diagnosis of primary MFH of the lungs may be helpful in such cases. CASE: A 37-year-old male presented with a large, irregular mass in the inferior and middle lobes on chest roentgenography as well as on computed tomography. Two bronchoscopies were performed, with the diagnosis of undifferentiated large cell carcinoma. After surgical resection a more sophisticated pathologic analysis, including immunohistochemical and ultrastructural studies, revealed a primary MFH of the lungs. Revision of the bronchial brushing cytology disclosed many spindle-shaped cells with a "comet" configuration, strongly suggestive of MFH. CONCLUSION: The bronchial brushing cytology features of spindle-shaped and bizarre, multinucleated giant cells with a comet appearance may be the key to the cytomorphologic diagnosis of MFH.     

Detection of infection with human immunodeficiency virus type 1 before seroconversion: correlation with clinical symptoms and outcome

Early (pre-seroconversion) infection with human immunodeficiency virus type 1 (HIV-1) was identified in 50 of 267 participants in the Multicenter AIDS Cohort Study. These 50 men had a positive EIA result, which detected IgM antibody (n = 35), p24 antigen, or serum HIV RNA (n = 15) at their last "seronegative" visit. At that visit, the mean CD4 lymphocyte number (890/mm3 vs. 1038/mm3) was significantly lower than in men who subsequently seroconverted but had no evidence of early infection. The decline in CD4 cells was slower and the duration of AIDS-free time longer in the 19 men who were symptomatic in comparison to the 31 asymptomatic men with early infection, but differences were not significant.     

Attempted suicide--a challenge for the trauma surgeon?]

The data from 767 patients after a suicide attempt or suicide were analyzed retrospectively. Skeletal damage was present in 52% of the patients. This was also the highest percentage in the breakdown of the injury patterns, followed by damage of the central nervous system (26.6%). Injuries to parenchymatous organs (20.1%) took third place. Extensive soft tissue injuries were diagnosed in 18.1% and relevant vascular lesions in 16% of suicide cases. At the same time, the high percentage of multiple trauma patients (22.9%) reflects the severity and the extent of injuries suffered in the application of "violent methods". Injuries of suicide cases involving violence often resemble those of serious road traffic accidents. In contrast to unselected patients, the injury pattern of suicide cases with multiple trauma is dominated by jumps from a great height and being run over by a train. However, when unusual suicide techniques are used, the surgeon's experience may soon become insufficient. To our knowledge, special traumatology wards provide the best available diagnosis and emergency care for these patients unless they have suffered purely trivial injuries.