Biomechanical evaluation of spinal stability after disc injury in a porcine model

The biomechanical effects of disc injury on flexion-extension were investigated in nine fresh porcine functional spinal units. Under 12 N-m in extension and 6 N-m in flexion, the range of motion among intact specimens were 23.11 degrees -33.29 degrees (mean = 26.07 degrees , SD = 3.25 degrees ), which shifted to 28.04 degrees -38.46 degrees (mean = 31.69 degrees , SD = 3.50 degrees ) when discs were injured. Similarly, the neutral zones among intact and disc injured specimens were 4.88 degrees -12.75 degrees (mean = 9.32 degrees , SD = 2.60 degrees ) and 9.50 degrees -24.43 degrees (mean = 16.80 degrees , SD = 4.69 degrees ) respectively. To obviate the differences between tested specimens, the changes of neutral zone and the range of motion after disc injury were normalized and expressed as ratios as compared to the same items before disc injury. The neutral zone ratio ranged from 1.29 to 3.18 (mean = 1.87, SD = 0.55, p < 0.01). For range of motion, it ranged from 1.13 to 1.42 (mean = 1.22, SD = 0.09, p < 0.01). The change of flexibility coefficient, however, was statistically insignificant in either flexion or extension. The model presented defines the range of motion, the neutral zone as well as the flexibility coefficient under a specific load. It suggests that major spinal instability can be elicited by a minimum flexion-extension moment, as reflected by a profound change of the neutral zone, after disc injury.     

Passive exercise system: effect on muscle activity, strength, and lean body mass.

There is little information concerning the effects of passive exercise training in healthy humans. This prompted an investigation to evaluate muscle activity and the associated changes in strength and lean body mass resulting from a passive exercise program. Twenty-eight healthy volunteers, aged 26 to 44 years, participated in this six-week study. Lean body mass changes were evaluated by tetrapolar bioelectric impedance measurements, strength changes by isokinetic strength evaluation, and muscle activity by surface EMG techniques. Reproducible muscle activity was recorded in all three muscles studied during two of three preselected exercises. This involuntary muscle activity was attributed to fusimotor and postural reflexes. No significant change (p greater than .05), however, occurred in muscle strength or lean body mass at the end of the six weeks. Lack of these physiologic changes in light of the documented muscle activity is attributed to insufficient training effect.     

Patient attitude towards waiting in an outpatient clinic and its applications.

Patient waiting time in outpatient clinics is often the major reason for patients' complaints about their experiences of visiting outpatient clinics. Therefore, patient satisfaction with waiting time plays a crucial role in the process of health quality assurance or quality management. This paper reports the results of a survey on patient attitude towards waiting in an outpatient surgery clinic. Generally patients appear reasonably satisfied if they wait no more than 37 minutes when arriving on time, and no more than 63 minutes when late for appointments. Patients coming up to 15 minutes early are prepared to take full responsibility for the extra waiting caused, but the patients coming even earlier intend to be seen earlier and are only prepared to wait 15 minutes longer than otherwise. The potential applications of patient attitude towards waiting in the quality assurance process, ie setting up waiting time limits and designing patient dispatching rules, are also discussed.     

Effect of cisplatin chemotherapy on extracortical tissue formation in canine diaphyseal segmental replacement

The reconstruction of large bone and joint defects after the resection of malignant tumors remains a major challenge. Chemotherapy has significantly lowered the risk of metastasic disease, but complications associated with reconstructive techniques continue to result in late morbidity. In the present study, biomechanical torsion testing, gait analysis, and histomorphometric and scanning electron microscopic evaluations of 24 dogs were used to examine the effects of preoperative and postoperative administration of cisplatin on the biologic fixation of a porous-coated segmental replacement prosthesis. The chemotherapy consisted of four cycles of cisplatin administered at a dosage of 75 mg/m:² preoperatively or postoperatively. The healing was enhanced by use of an autogenous corticocancellous bone graft. The graft was placed evenly around the prosthesis and the adjacent femoral cortex. Mechanical analyses of torsional stiffness, yield strength, and maximum strength revealed no statistically significant differences between the groups at 12 weeks. Such lack of difference was mainly due to the penetration of highly organized fibrous tissue into the porous surface; this provided strong fixation of the implant to bone even in the absence of bone ingrowth. Although bone ingrowth into the prostheses was not affected, electron microscopic, histomorphometric, and radiologic analyses showed a clear difference in the formation of new bone around the prosthesis. Preoperative chemotherapy did not alter the formation of new bone, but specimens from animals treated postoperatively with cisplatin showed significantly less bone graft resorption and less new bone formation. Hence, the effect of cisplatin administration caused only a temporary delay, not a permanent effect, on extracortical capsule formation. The formation of extracortical bone and soft tissue might prevent debris-incised osteolysis and, therefore, prevent late complications by forming a tight capsule around the bone-prosthetic interface.     

脑梗塞患者血清脂蛋白（a）测定及其临床意义

应用酶标法测定58例脑梗塞患者和56例健康对照者血清脂蛋白(a)[LP(a)]含量,并同时测定了其他脂代谢指标,对其中26例脑梗塞患者还测定了血浆纤维蛋白溶解(简称纤溶)指标。结果表明脑梗塞组存在显著的脂代谢和纤溶功能紊乱。LP(a)含量增高,与所测脂代谢、纤溶指标无显著相关,是脑梗塞发病独立的危险因素。     

体外循环对瓣膜置换术病人血细胞胰岛素受体和红细胞ATP含量的影响

目的：观察体外循环（ＣＰＢ）对１０例瓣膜置换术病人全血细胞胰岛素受体和红细胞ＡＴＰ含量的影响。方法：利用放射配体结合试验，测定全血细胞胰岛素受体密度和亲和力；用高效液相色谱法测定红细胞ＡＴＰ含量，同时监测血糖和胰岛素浓度。结果：转流３０分钟，血细胞高亲和胰岛素受体（Ｒ１）密度明显增加（Ｐ＜０．０１），亲和力（Ｋ１）明显降低（Ｐ＜０．０１），低亲和胰岛素受体（Ｒ２）密度也明显增加（Ｐ＜０．０１），但亲和力（Ｋ２）变化不大（Ｐ＞０．０５）；停机３０分钟，上述变化有所恢复，但未到转流前的水平。转流３０分钟红细胞ＡＴＰ含量明显降低（Ｐ＜０．０１），并持续到停机后３０分钟，同时伴随血糖明显升高（Ｐ＜０．０１），胰岛素／血糖比值明显降低（Ｐ＜０．０１）。结论：ＣＰＢ可致血细胞胰岛素受体密度增加而亲和力下降，以及红细胞ＡＴＰ含量下降。     

Nephrectomy during operative management of retroperitoneal sarcoma

Background: Complete resection of a retroperitoneal sarcoma often requires removal of adjacent organs. In this study we evaluated the role of nephrectomy during operation for retroperitoneal sarcoma. Methods: Between July 1982 and July 1995, 75 of the 371 (20%) patients who underwent resection of retroperitoneal sarcoma at MSKCC underwent concommitant nephrectomy. Data concerning the reasons for nephrectomy, degree of sarcomatous renal involvement, and survival were retrospectively analyzed. Results: Fifty-four patients (72%) underwent nephrectomy during the initial resection, and 21 (28%) during a resection of a recurrent or persistent tumor. The most common reason for nephrectomy was total encasement by sarcoma (n=40; 53%), followed by dense adherence of the tumor to the kidney (n=21; 28%), and the direct invasion of the kidney by tumor (n=2; 3%). Pathology demonstrated an absence of kidney invasion in the majority of cases (55 of 75; 73%). Renal capsular invasion was present in 11 of 75 (15%), renal parenchymal invasion in 7 of 75 (9%), and renal vein invasion in 2 of 75 (3%) of cases. There were no significant differences in survival based on degree of sarcoma involvement of the kidney, tumor grade, or whether the resection was for primary or recurrent disease. The 53 patients who underwent a complete gross resection of all tumor had a significantly improved long-term survival compared to the 20 patients who did not (50% versus 20% DFS at 5 years, respectively; p<0.001). Conclusions: Decisions for concomitant nephrectomy during resection of retroperitoneal sarcoma should be based on whether this maneuver will provide a complete resection of all gross tumor, in which case the long-term disease-free survival of 50% is comparable to the reported 5-year survival of all patients with retroperitoneal sarcoma who are completely resected. Presented at the 49th Annual Cancer Symposium of the Society of Surgical Oncology, Atlanta, Georgia, March 21–24, 1996.     

Fulminant childhood hemophagocytic syndrome mimicking histiocytic medullary reticulosis. An atypical form of Epstein-Barr virus infection.

Ten cases of pediatric fulminant hemophagocytic syndrome, encountered between 1986 and 1989, are described. They occurred in the summer, and the patients presented with fever, jaundice, hepatosplenomegaly, pancytopenia, coagulopathy, and abnormal liver function. Bone marrow studies revealed infiltration by atypical T-lymphoid cells, rare B immunoblasts, and mature histiocytes with hemophagocytosis. Initially, histiocytic medullary reticulosis was suspected in six cases. The clinical course was characterized by rapid deterioration, with a mean period of 16 days from onset of fever to death. The main causes of death were coagulopathy with multiple organ failure and opportunistic infection. In seven of eight cases studied by serologic assay and Southern blot hybridization, acute or active Epstein-Barr virus (EBV) infection was documented. It is suggested that an atypical or fulminant form of primary EBV infection distinct from classic infectious mononucleosis was prevalent in previously healthy children in Taiwan. Younger age involvement and seasonal clustering were characteristic of the disorder described.