An in vitro biomechanical study of a hinged external fixator applied to an unstable elbow

Details of the mechanical properties of hinged external fixators are essential to use the fixator properly in the clinical setting. A hinged external fixator (Dynamic Joint Distractor 2) was attached to the lateral side of 7 cadaveric elbows. Cantilever lateral bending tests were performed at 3 flexion angles in varus and valgus directions. Varied states of joint contact and axial loading were studied. Stiffness of the construct was calculated with uniaxial loading. Stiffness decreased with increased elbow flexion. Gap creation made the system less stiff. Axial loading made the system stiffer, especially in valgus testing. Stiffness in varus was approximately 4 times that in valgus. Lateral fixator application with half pins is most effective for protecting against varus-producing forces. When using the external fixator for unstable elbows, attention should be paid to the status of the articular surfaces and the integrity of the ligaments, and this should also be noted for elbow position during rehabilitation.     

Neuroprotective effect of 1-methyl-1,2,3,4-tetrahydroisoquinoline on cultured rat mesencephalic neurons in the presence or absence of various neurotoxins

1-Methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) is an endogenous brain amine and its content in parkinsonian brain is decreased compared with that in control brain. There is some evidence that 1MeTIQ protects dopaminergic neurons against dysfunction such as that seen in Parkinson's disease. In this study, we examined the neuroprotective effect of 1MeTIQ against four dopaminergic neurotoxins, 1-methyl-4-phenylpyridinuim ion, 6-hydroxydopamine, rotenone, and l-benzyl-1,2,3,4-tetrahydroisoquinoline, in cultured rat mesencephalic neurons. 1MeTIQ exerted neuroprotective action against all these toxins. Furthermore, (R)-1MeTIQ was neuroprotective, while (S)-1MeTIQ had little effect, indicating that the effect is stereoselective. The protective action of 1MeTIQ was most effective in mesencephalic neurons, especially in tyrosine hydroxylase-positive neurons. 1MeTIQ showed no affinity for dopamine receptors and did not influence the inhibition of mitochondrial respiratory complex I by rotenone, 1-methyl-4-phenylpyridinuim ion, or 1-benzyl-1,2,3,4-tetrahydroisoquinoline. These results raise the possibility that 1MeTIQ indirectly acts as an anti-oxidant such as the induction of anti-oxidative enzymes, because all these four neurotoxins can burden oxidative stress in common. This is the first report to confirm a protective effect of 1MeTIQ at the cultured neuron level, and it may have potential as a lead compound for the development of new agents to treat Parkinson's disease.     

Patients homozygous for the T435N mutation of succinyl-CoA:3-ketoacid CoA Transferase (SCOT) do not show permanent ketosis

Succinyl-CoA:3-ketoacid CoA transferase (SCOT; locus symbol OXCT; E.C. 2.8.3.5) is the main determinant of the ketolytic capacity of tissues. Hereditary SCOT deficiency causes episodic ketoacidosis. Permanent ketosis has been regarded as a pathognomonic feature of SCOT deficiency. There are three SCOT-deficient patients from a small region in Japan and they have not manifested permanent ketosis, even though their ketoacidotic crises were as severe as those of other SCOT-deficient patients. All three were homozygous for the T435N mutation. Transient expression analysis of wild-type and mutant cDNA showed that the T435N mutant retained significant residual SCOT activities (20% for that of the wild-type at 39.5 degrees C, 25% at 37 degrees C, and 50% at 30 degrees C). The difference of residual SCOT activities at these temperatures in expression analyses was due to differences in the level of the mutant protein. SCOT activity of the T435N protein was more vulnerable than the wild-type to heat treatment at 42 degrees C and 55 degrees C. These temperature-sensitive characteristics of the mutant protein may explain, in part, why the patients developed ketoacidotic crises during febrile illness. In SCOT-deficient patients retaining some residual activity, permanent ketosis may be absent.     

MRI reveals fetus in fetu in the mediastinum

Fetus in fetu is an extremely rare condition in which a fetiform calcified mass is contained within the newborn or infant, often in the retroperitoneal cavity. We report a case of a fetus in fetu in the posterior mediastinum of a newborn. The prospective diagnosis was made by fetal US and MRI and confirmed by postnatal plain radiograph, CT and MRI.     

A comparative study of mini-external fixation systems used to treat unstable metacarpal fractures

We compared the biomechanical properties, clinical versatility, application ease, and financial cost of 7 mini-external fixation systems used to treat unstable metacarpal shaft fractures with segmental bone loss. Attached to a maple dowel fracture model, each fixator was tested in axial compression, lateral 4-point bending, 45 degrees apex-dorsal 4-point bending, and torsion. The EBI DynaFix system had the highest overall rigidity values and was highly versatile; the Synthes/AO Mini-External Fixator had intermediate rigidity values and was the lightest system tested; the Howmedica Mini-Hoffmann fixator was substantially less rigid than all the other tested constructs but was the most versatile. Devices constructed with polymethylmethacrylate and Kirschner wires were rigid, lightweight, and inexpensive. Routine use of these devices is discouraged, however, because of unacceptable loosening at the pin-cement interface during testing and because of difficulties encountered during construction and application. None of the external fixation systems tested was superior in all the parameters analyzed.     

A case of advanced colon cancer with metastases to both the Virchow's and the paraaortic lymph nodes that achieved complete long-term response with levofolinate.5-FU therapy

A 48-year-old woman presented with a tumor in the supra-clavicular fossa. Under a diagnosis of advanced ileocecal colon cancer with metastases to Virchow's and the paraaortic lymph nodes, ileocecal resection was performed. After surgery, the patient was given 5-FU infused continuously at 500 mg/body per day, and levofolinate was dripped intravenously at 100 mg/body over 2 hours for 5 successive days per week. Two cycles were repeated each week. She was then intravenously given weekly modulation chemotherapy consisting of 125 mg/body levofolinate and 500 mg/body of 5-FU for about 5 months on an outpatient basis. Furthermore, the same administration schedule was continued bi-weekly for 1 year and 4 months. As a result, the enlarged paraaortic lymph nodes had completely disappeared by 5 months after administration of levofolinate.5-FU. The Virchow's lymph node metastasis has not been palpable for 11 months. Throughout the period of treatment, there were no severe side effects and as of this writing, no sign of recurrence for 3 years after surgery. A high quality of life has been maintained. In conclusion, this case seems significant from the viewpoint of the complete long-term response to a moderate dose of levofolinate.5-FU therapy and the long duration of administration, which was tolerable with few side effects. Moreover, we identified the presence of TS and DPD using immunohistochemical staining techniques, when both primary tumor and regional lymph nodes were all negative for the stain test. It was suggested that this cancer especially would responded to 5-FU chemotherapy.     

Periampullary tumors: high-spatial-resolution MR imaging and histopathologic findings in ampullary region specimens

PURPOSE: To prospectively determine the magnetic resonance (MR) signal intensity characteristics of structures of the ampullary region and to assess the potential use of MR imaging in evaluation of the extent of periampullary tumors in resected specimens. MATERIALS AND METHODS: Twenty-five specimens from the ampullary region obtained in four autopsy cases without periampullary tumors and in 21 patients with periampullary tumors were examined with a 1.5-T MR system and a circular surface coil with 5-inch (12.7-cm) diameter. High-spatial-resolution MR images were obtained with field of view of 100 x 100 mm, matrix of 256 x 256 or 512 x 256, and section thickness of 2 mm. MR imaging findings were compared with histopathologic findings. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissues were evaluated by two radiologists. RESULTS: T1- and T2-weighted MR images clearly depicted normal structures in the ampullary region that included Oddi muscle, duodenal wall, common bile duct, and pancreas; these findings corresponded well with histologic findings. In 20 (95%) of 21 tumors, high-spatial-resolution MR imaging depicted location and extension of periampullary tumors precisely. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissue were 88%, 100%, 96%, 100%, and 94%, respectively. CONCLUSION: In this study, MR imaging correctly depicted location, extension, and origin of tumor. High-spatial-resolution MR imaging has potential for presurgical staging of tumors in this region.