Biologic enhancement of spinal fusion

Scientific advances in the past decade have generated considerable clinical interest in developing biologic tools that may ultimately enhance spinal fusion. This article reviews the current understanding of each of these and other fusion-enhancing tools with particular attention to the results of in vivo animal experimentation and, where available, objective clinical data.     

Comparative study between intra-anal sponge and needle electrode for electromyographic evaluation of constipated patients

PURPOSE: The aim of this study was to compare the intra-anal sponge electrode with the conventional needle electrode for electromyography of the pelvic floor in constipated patients. MATERIALS AND METHODS: Forty consecutive patients (27 females) with a mean age of 64.3 (range, 15-87) years who had chronic constipation were prospectively evaluated for electromyographic evidence of nonrelaxation or paradoxical contraction of the puborectalis and external anal sphincter during simulated defecation. The soft intra-anal sponge electrode and then the concentric needle electrode were used in each patient as an internal control. Furthermore, in all patients, cinedefecography was used as an independent standard to confirm the diagnosis. Agreement was calculated using the kappa statistic. RESULTS: Confirmation of needle electromyography was noted in 19 of 20 patients (95 percent) who had sponge electromyographic evidence of paradoxical activity. Similarly, concurrence was noted in 19 of 20 patients (95 percent) with normal relaxation of the puborectalis observed with the sponge electrode. Agreement between needle and sponge electromyography was very good (kappa = 0.9), between needle electromyography and cinedefecography was fair (kappa = 0.4), and between sponge electromyography and cinedefecography was moderate (kappa = 0.5). Furthermore, needle electromyography was more painful in all patients compared with sponge electromyography. CONCLUSION: The soft sponge surface intra-anal electrode is an excellent alternative to the needle electrode for assessment of puborectalis activity in constipated patients. Sponge electromyography has the advantage of being as accurate as, but less painful than, needle electromyography.     

Eosinophilic foreign body granuloma after multiple self-administered bee stings

A bee sting can cause a foreign body granuloma of the skin, due to activated macrophages at the stinging site. A 52-year-old woman presented with a large doughnut-shaped ulcerative tumour on the left side of her face. A bean-sized facial papule had grown to a 4.0 x 3.9 x 1.1 cm mass after multiple bee stings induced by herself over a period of 1 year. Histology showed epidermal ulceration with granulomatous inflammatory cell infiltration of many eosinophils. No micro-organisms or foreign bodies were identified. Intralesional triamcinolone acetonide was not effective, but an excellent outcome was obtained using carbon dioxide laser vaporization of the lesion.     

Impact of exogenous growth factors on proliferation and chemosensitivity of minimal residual acute myeloid leukemia

The biological heterogeneity of AML makes growth factor augmentation of cell cycle-dependent chemotherapy unlikely to be successful for all patients. Patients whose leukemic cells empirically demonstrate cytokine-induced chemosensitization in vitro might benefit from the concurrent administration of growth factors during consolidation chemotherapy. We have explored the growth factor-dependence and response of primary bone marrow samples from patients with AML at diagnosis, remission, and relapse to determine whether minimal residual leukemia remains growth factor-responsive. Most cases of AML studied at all phases of treatment were growth factor-responsive. Growth factor response of occult remission clonogenic leukemic precursors (CFU-L) was usually concordant with their response at diagnosis. Occult CFU-L were markedly resistant to cytosine arabinoside (median LD99% 20 microM); preincubation with IL-3 or GM-CSF did not significantly improve their ara-C sensitivity. While occult remission CFU-L appear to remain growth factor-responsive, it appears unlikely that growth factor augmentation of consolidation chemotherapy will overcome the important problem of drug resistance of residual leukemia.     

Synaptic transmission and hippocampal long-term potentiation in olfactory cyclic nucleotide-gated channel type 1 null mouse

Field potential recording was used to investigate properties of synaptic transmission and long-term potentiation (LTP) at Schaffer collateral-CA1 synapses in both hippocampal slices of mutant mice in which the alpha-subunit of the olfactory cyclic nucleotide-gated channel (alpha3/OCNC)1 was rendered null and also in slices prepared from their wild-type (Wt) littermates. Several measures of basal synaptic transmission were unaltered in the OCNC1 knockout (KO), including maximum field excitatory postsynaptic potential (fEPSP) slope, maximum fEPSP and fiber volley amplitude, and the function relating fiber volley amplitude to fEPSP slope and paired-pulse facilitation. When a high-frequency stimulation protocol was used to induce LTP, similar responses were seen in both groups [KO: 1 min, 299 +/- 50% (mean +/- SE), 60 min, 123 +/- 10%; Wt: 1 min, 287 +/- 63%; 60 min, 132 +/- 19%). However, on theta-burst stimulation, the initial amplitude of LTP was smaller (1 min after induction, 147 +/- 16% of baseline) and the response decayed faster in the OCNC1 KO (60 min, 127 +/- 18%) than in Wt (1 min, 200 +/- 14%; 60 min, 169 +/- 19%). Analysis of waveforms evoked by LTP-inducing tetanic stimuli revealed a similar difference between groups. The development of potentiation throughout the tetanic stimulus was similar in OCNC1 KO and Wt mice when high-frequency stimulation was used, but OCNC1 KO mice showed a significant decrease when compared with Wt mice receiving theta-burst stimulation. These results suggest that activation of cyclic nucleotide-gated channels may contribute to the induction of LTP by weaker, more physiological stimuli, possibly via Ca2+ influx.     

Pancreatic tuberculosis in non-immunocompromised patients: reports of two cases, and a literature review

We present two cases of biopsy proven tuberculosis of the pancreas in non-immunocompromised patients diagnosed and treated in our unit within the last 14 years. The first case presented with abdominal pain and fever, and the second with iron deficiency anaemia and severe weight loss. In both cases abdominal ultrasound and computed tomography suggested a pancreatic carcinoma. There was no pulmonary or intestinal tuberculosis. The tuberculin skin test was positive. Upon exploratory laparotomy the macroscopic appearance of the pancreas was that of an inoperable pancreatic carcinoma. Following the histological diagnosis of pancreatic tuberculosis, both patients were successfully treated with triple antituberculous therapy for 6 months. Isolated pancreatic tuberculosis is an extremely rare disease with only 41 cases in non-immunocompromised patients reported worldwide (1966-1997). It is a curable disease and should be considered in the differential diagnosis of a pancreatic mass or abscess shown on ultrasound or computed tomography, especially in developing countries, where tuberculosis is common.     

Controlling signaling with a specifically designed Gi-coupled receptor

We are developing a system to control G protein signaling in vivo to regulate a broad range of physiologic responses. Our system utilizes G protein-coupled peptide receptors engineered to respond exclusively to synthetic small molecule ligands and not to their natural ligand(s). These engineered receptors are designated RASSLs (receptor activated solely by a synthetic ligand). We have made two prototype RASSLs that are based on the human kappa opioid receptor. Small molecule drugs that activate the kappa receptor are nonaddictive and safe to administer in vivo. Binding and signaling assays reveal 200-2000-fold reductions in the ability of our RASSLs to bind or be activated by dynorphin, an endogenous peptide ligand of the kappa opioid receptor. In a high-throughput signaling assay, these prototype RASSLs expressed in Chinese hamster ovary K1 cells showed little or no response to a panel of 21 opioid peptides but still signaled normally in response to small molecule drugs such as spiradoline. Activation of a RASSL by spiradoline also caused proliferation of rat-1a tissue culture cells. These data provide evidence that G protein-coupled receptors can be made into RASSLs. The potential in vivo applications for RASSLs include the positive enrichment of transfected cells and the development of new animal models of disease.     

Shaker-1 mutations reveal roles for myosin VIIA in both development and function of cochlear hair cells

The mouse shaker-1 locus, Myo7a, encodes myosin VIIA and mutations in the orthologous gene in humans cause Usher syndrome type 1B or non-syndromic deafness. Myo7a is expressed very early in sensory hair cell development in the inner ear. We describe the effects of three mutations on cochlear hair cell development and function. In the Myo7a816SB and Myo7a6J mutants, stereocilia grow and form rows of graded heights as normal, but the bundles become progressively more disorganised. Most of these mutants show no gross electrophysiological responses, but some did show evidence of hair cell depolarisation despite the disorganisation of their bundles. In contrast, the original shaker-1 mutants, Myo7ash1, had normal early development of stereocilia bundles, but still showed abnormal cochlear responses. These findings suggest that myosin VIIA is required for normal stereocilia bundle organisation and has a role in the function of cochlear hair cells.     

Exit from mitosis in Drosophila syncytial embryos requires proteolysis and cyclin degradation, and is associated with localized dephosphorylation

The cyclin proteolysis that accompanies the exit from mitosis in diverse systems appears to be essential for restoration of interphase. The early syncytial divisions of Drosophila embryos, however, occur without detectable oscillations in the total cyclin level or Cdk1 activity. Nonetheless, we found that injection of an established inhibitor of cyclin proteolysis, a cyclin B amino-terminal peptide, prevents exit from mitosis in syncytial embryos. Similarly, injection of a version of Drosophila cyclin B that is refractory to proteolysis results in mitotic arrest. We infer that proteolysis of cyclins is required for exit from syncytial mitoses. This inference can be reconciled with the failure to observe oscillations in total cyclin levels if only a small pool of cyclins is destroyed in each cycle. We find that antibody detection of histone H3 phosphorylation (PH3) acts as a reporter for Cdk1 activity. A gradient of PH3 along anaphase chromosomes suggests local Cdk1 inactivation near the spindle poles in syncytial embryos. This pattern of Cdk1 inactivation would be consistent with local cyclin destruction at centrosomes or kinetochores. The local loss of PH3 during anaphase is specific to the syncytial divisions and is not observed after cellularization. We suggest that exit from mitosis in syncytial cycles is modified to allow nuclear autonomy within a common cytoplasm.     

Up-regulation of type 2 iodothyronine deiodinase mRNA in reactive astrocytes following traumatic brain injury in the rat

Type 2 5'-deiodinase (5'-D2), which converts thyroxine to the more active thyroid hormone 3,5,3'-triiodothyronine (T3), is believed to be an important source of intracellular T3 in the brain. The activity of this enzyme is increased in hypothyroidism and decreased in hyperthyroidism, and as such, it serves an important role to protect the brain from wide fluctuations in T3 during changes in thyroidal state. Although it has been hypothesized that T3 may facilitate neuronal regeneration after CNS injury, the 5'-D2 response to brain injury is unknown. To assess the 5'-D2 mRNA response to injury, we performed in situ hybridization following traumatic brain injury. In unlesioned animals, 5'-D2 mRNA was undetectable. At 3 days posttrauma, 5'-D2 mRNA was detected in ipsilateral cortex near the contusion. A significant further increase of 5'-D2 mRNA was noted 7 days posttrauma in both hippocampus and cortex. Similar response was also observed on the contralateral side. Colocalization of 5'-D2 mRNA with glial fibrillary acidic protein indicates that reactive astrocytes were the major cellular source for the trauma-induced 5'-D2 expression. These data demonstrate, for the first time, a trauma-induced, astrocytic up-regulation of 5'-D2 mRNA, suggesting a potential role for T3 action in adult brain's response to injury and recovery.