Simultaneous anterior-posterior thoracolumbar spine surgery.

The purpose of this article is to report our experience with simultaneous anterior and posterior approach spine surgery. The patient is placed in the decubitus position. Two teams of spine surgeons simultaneously perform surgical approaches, decompression, arthrodesis, and instrumentation. No repositioning, repreparing, or redraping is necessary. Twelve patients with varying lesions underwent this procedure. This technique is presented as an alternative to the sequential single-staged anterior and posterior procedure and the two-staged procedures performed under separate anesthetics. Although no statistical significance can be concluded, we believe a larger series will demonstrate that operative time is decreased, potential risks of repositioning are avoided, and superior exposure and mobilization of spinal elements are afforded. Exposure, decompression, and stabilization posteriorly is feasible in the decubitus position.

MR imaging of mediastinal lymph nodes: evaluation using a superparamagnetic contrast agent.

The purpose of this study was to determine whether intravenous injection of a magnetic resonance (MR) contrast agent, ultrasmall superparamagnetic iron oxide (ferumoxtran-10), can be useful in characterizing lymph nodes in patients with lung cancer. Twelve patients with known or suspected lung cancer were studied. Pre- and postcontrast injection of ferumoxtran-10 MR scans of the chest were obtained. Analysis of the signal intensities and bronchoscopic fine needle aspiration of a single node were performed in each patient. Six of 12 patients had a final diagnosis of lung cancer. T1-weighted images were best for localizing mediastinal lymph nodes. Signal intensity changes before and after contrast were best visualized on T2-weighted and gradient-echo images. All four patients with lung cancer who had nodes positive for malignancy at biopsy had no change in signal intensity of the nodes on T2 images. The signal intensity decreased in the remaining two patients, and the nodes were benign. Of the eight patients with benign disease, five had no change in signal intensity of the nodes. Therefore the sensitivity for tumor involvement of the nodes is 100%, but the specificity is only 37.5%. Ferumoxtran-10 is a contrast agent that can alter the signal intensity of lymph nodes. Lack of signal change may be due to malignant or inflammatory change. Studies in a larger population of lung cancer patients may help to characterize the utility of this agent further. J. Magn. Reson. Imaging 2000;12:899-904.

Bedside orthopedic procedures.

Orthopedic bedside procedures commonly are performed and are appropriate. As the complexity of patient needs increases and resources are stretched, more patient care, including orthopedic procedures, will be performed in cost-effective but safe environments such as the monitored intensive care setting. Medical technology and expertise are expanding rapidly, and these improved resources can and will allow more procedures to be performed safely and effectively outside the operating room. The decision to perform a specific procedure on a specific patient in a specific environment requires careful consideration of the risk to benefit ratio. This consideration should involve the patient, the physicians, and the entire health care team.

Immunomodulator OM 163-induced reversal of tumor-mediated immunosuppression and downregulation of TGF-beta 1 in vivo.

Although PROb colonic tumor cells are immunosuppressive, the immunomodulator OM 163 induced the disappearance of macroscopic peritoneal nodules in 50% of rats bearing a peritoneal carcinomatosis (p.c.) induced by PROb cells. When the p.c. developed, the number of T lymphocytes was low and the expression of interferon (IFN)-gamma mRNA in tumor nodules decreased very rapidly. The TGF-beta 1 secreted by PROb cells could be responsible for the immunosuppression, because the PROb cell supernatant inhibited IFN-gamma production and T lymphocyte proliferation. When the rats were treated with OM 163, an infiltration of T lymphocytes was observed in tumor nodules, as well as a high expression of the IFN-gamma mRNA. The antitumor efficiency of the immunomodulator OM 163 could be explained in part by a direct effect of OM 163 on T lymphocytes, because in vitro it stimulated the proliferation and the secretion of IFN-gamma of T lymphocytes. OM 163 could also act at the TGF-beta 1 level. Although OM 163 alone or in combination with IFN-gamma did not modify the TGF-beta 1 secretion by PROb cells in vitro, the expression of the TGF-beta 1 mRNA and the TGF-beta 1 protein content was decreased in vivo in treated tumor nodules.

A sensitive two-site enzyme immunoassay for the detection of rat interferon-gamma in biological fluids.

Two noncompeting monoclonal antibodies (mAbs) directed to rat interferon-gamma (IFN-gamma) were used in a sensitive two-site enzyme-linked immunosorbent assay (ELISA). This permitted quantitation of rat IFN-gamma in culture medium, and serum and was quicker and more sensitive than the conventional antiviral bioassay. A standard curve was linear between 0.1 (15 pg) and 10 (1,500 pg) U/ml. There was no reaction with rat IFN-alpha or -beta or human IFN-gamma, but mouse IFN-gamma was detected with a lower limit of sensitivity of 300 U/ml. Complement-dependent inactivation of rat IFN-gamma reduced the sensitivity of the ELISA approximately seven-fold but this could be overcome by adding ethylenediamine tetraacetic acid (EDTA, 10 mM) or other anticomplementary substances to the serum samples. IFN-gamma activity determined by ELISA and bioassay decreased in parallel upon heat denaturation and pH 2.5 treatment, but proteases caused a relatively greater reduction in biological activity.

Effect of human recombinant tumour necrosis factor and rat gamma interferon on nitrosomethylurea-induced mammary tumours.

We have used the nitrosomethylurea-induced rat mammary tumour model to study the effects of parenteral administration of human recombinant tumour necrosis factor (rHu-TNF) and rat gamma interferon (IFN-gamma). An inbred strain of tumour bearing female Ludwig/Wistar/Olac rats were randomised to either treatment or control groups. Two independent studies showed that combined treatment with rHu-TNF and rat IFN-gamma induced significant tumour regression over 4 weeks (P = 0.004, P = 0.005 respectively). Treatment with either rHu-TNF or rat IFN-gamma given individually did not affect the overall rate of tumour growth (P = 0.157 and 0.40 respectively) although an initial reduction in tumour size was observed during the first few days after injection. Measurement of circulating oestradiol levels in groups in which maximum tumour regression was observed showed no statistically significant difference when compared to the control group. Similarly, measurement of oestrogen receptor content showed no statistically significant difference between rHu-TNF-gamma or rat-IFN-gamma treatment or combined treatment of rHu-TNF and IFN-gamma with the control group. We conclude from these observations that combined therapy with rHu-TNF and rat IFN-gamma may prove to be useful new forms of treatment for human breast cancer.

Antiviral activity of recombinant rat interferon gamma in immunologically impaired and immunosuppressed rats.

Treatment of Wag/Rij rats with recombinant rat interferon gamma (rRIF-gamma) resulted in complete protection against a lethal pseudorabies virus (PRV) infection. To investigate whether the protection resulted from direct inhibition of virus replication or from a stimulation of immune mechanisms, we tested rRIF-gamma activity in naturally immunocompromised and artificially immunosuppressed rats. The antiviral effect of rRIF-gamma was not abolished in silica- and carrageenan-treated, phagocyte-depleted rats. Immunologically immature newborn and T cell-deficient nude rats were also protected under a regime of rRIF-gamma treatment as well as whole body gamma-irradiated rats. Sera of the protected rats were devoid of PRV-neutralizing antibodies. Our results indicate that the protective activity of rRIF-gamma is based on direct inhibition of virus replication; stimulation of the immune system is not required but may be responsible for protection upon challenge several weeks after infection.

Gallium scintigraphy for diagnosis of septic arthritis and osteomyelitis in children.

Thirty-four children with presumptive acute osteomyelitis or septic arthritis underwent early gallium-67 citrate scintigraphy and have been retrospectively reviewed. Diagnostic accuracy using this technique was 91%. Gallium-67 citrate is a more reliable radiopharmaceutical agent for the detection of selected acute musculoskeletal infections than either technetium methylene diphosphonate or indium-111. However, the radiation dosage from gallium is higher than from other radiopharmaceutical agents, and the authors would recommend its use only in cases where the diagnosis cannot be made on the basis of clinical, laboratory, or plain roentgenographic criteria.

Elongation factor Tu isolated from Escherichia coli mutants altered in TufA and tufB.

In a previous paper we described a number of Escherichia coli mutants resistant to the antibiotic kirromycin. These mutants are altered in both tufA and tufB, the genes coding for elongation factor Tu (EF-Tu). We have now isolated EF-Tu in a homogeneous form from the mutant strains and have studied its function in polypeptide synthesis. These EF-Tu preparations were examined in renaturation studies of Qbeta RNA replicase, described in another paper. In order to characterize the factor we have inactivated the tufB gene by insertion of bacteriophage Mu or by an amber mutation. This enabled us to isolate EF-Tu as a single gene product derived from tufA (designated EF-TuA in contrast to the tufB product, which is called EF-TuB). Kirromycin-resistant EF-TuA did not respond to addition of the antibiotic in three assays: [(3)H]GDP exchange with EF-Tu-GDP at 0 degrees C, in vitro translation of poly(U), and kirromycin-induced GTPase activity of EF-Tu. In contrast, wild-type EF-TuA responded normally to the antibiotic in these assays. One of our mutants (LBE 2012) harbors the kirromycin-resistant EF-TuA and an EF-TuB that is able to bind kirromycin. This binding does not cause inhibition of protein synthesis, indicating that EF-TuB from LBE 2012 is unable to reach the ribosome under these conditions. The two types of EF-Tu from this mutant are equal in size but differ by 0.1 pH unit in isoelectric point. In the soluble fractions of LBE 2012 cells they are present in approximately equal amounts. Our results also show that the tufB gene is not necessary for bacterial growth.