Image-guided computer-assisted spine surgery: a pilot study on pedicle screw fixation

As the pedicle offers a strong point of attachment to the spine, several instrumentation systems using screws that go through the pedicle into the vertebral body have been developed to provide internal stability. All pedicle screw systems share the risk of damage to adjacent neural structures as a result of improper screw placement. A computer-assisted system allowing precise preoperative planning and real-time intraoperative interactive image localization has been implemented for spine instrumentation to optimize transpedicular spine fixation. A validation study was performed in an in vitro set-up drilling 20 pedicle pilot holes in lumbar vertebrae. An analysis in 77 histological cuts showed an ideal location in 70 with no case of injury to the pedicle cortex. We discuss initial clinical experience on cases of posterior lumbar stabilization. Interactive computer-assisted spine surgery provides an accurate and safe approach for transpedicular screw fixation and may provide a useful tool for optimization of spine surgery.

Conserved regulatory element involved in the early onset of Hoxb6 gene expression

We have identified a 338 bp DNA fragment, the lateral plate mesoderm (LPM) enhancer, that is highly conserved between mouse and human. The LPM enhancer directs gene expression into the posterior lateral plate mesoderm and hindgut endoderm at early stages of development. By reporter gene analysis in transgenic mice, we demonstrate that both mouse and human DNA sequences possess similar enhancer activity. The expression patterns of the transgene and Hoxb6 during early stages of mouse development are identical, suggesting that the LPM enhancer is involved in the initial activation of Hoxb6 gene expression in posterior regions of mammalian embryos.

[A prospective randomized study of parenteral and enteral nutrition in postoperative patients]

To evaluate the metabolic effects of balanced enteral nutrition (EN) and standard parenteral nutrition (PN, without glutamine) in post-operative patients, we performed a prospective randomized trial in 24 patients after gastrectomy or semi-colectomy. All patients had normal liver, kidney, heart and lung functions. patients of the enteral nutrition group received liquid Ensure (Abbott-Ross) while patients of the parenteral nutrition group received standard parenteral nutrition. Parenteral nutrition solutions consist of amino acids, fat emulsions, glucose, electrolytes, vitamins and trace elements. Subjects of the two groups received iso-nitrogenous and isocaloric nutritional regime for seven days (from POD+5 to POD+11). Weight loss in the parenteral nutrition group and the enteral nutrition group was 1.7 +/- 0.2 kg and 0.8 +/- 0.31 kg respectively. Cumulative nitrogen balance was -82 +/- 51 mg.kg-1/d in the parenteral nutrition group vs +70 +/- 7 mg.kg-1/d in the enteral nutrition group (P < 0.05). The results showed that balanced enteral nutrition had less weight loss and better cumulative nitrogen balance than standard parenteral nutrition in this protocol. More patients study will be needed.

Propagation of apertured Bessel beams

The propagation features of several apertured Bessel beams are numerically calculated. The calculations show that the relations of axial intensity versus propagation distance are similar to the radial distribution of the aperture functions, which may be helpful in choosing the proper aperture functions in experiments.

[A comparative study of fat emulsions clearance test using long chain triglycerides and medium chain triglycerides in volunteers]

Intravenous fat emulsions clearance test using long chain triglycerides (LCT) and medium chain triglycerides (50% MCT/LCT) were studied in ten healthy chinese volunteers. In the morning (8:00 AM) the lipid was infused continuously for 5 hours at rate of 0.17g.kg-1/h. There was an interval of two weeks between LCT and MCT/LCT. The peak concentration of serum triglyceride was smaller in MCT group. The area under concentration curve had significant difference between LCT and MCT groups (6108 +/- 461 vs 4495 +/- 362, P < 0.05). The serum free fatty acid was 628 +/- 42 in LCT and 1049 +/- 1 in MCT respectively in 5 hour (P < 0.001). The concentrations of very low-density lipoprotein (VLDL) in serum were increased in volunteers receiving LCT and MCT, but those of LDL and HDL were decreased. The blood sugar and cholesterol had no significant difference after lipids infusions. The study demonstrated that medium chain triglycerides was faster to be cleared than long chain triglycerides.

[Lymphatic metastasis in central direction and bowel axial direction in colonic cancers]

485 lymph nodes were founded by palpation in 44 R3 resected specimens of colonic cancers. In the bowel axial direction, the rate of lymphatic metastasis was 6.8%, which accound for 9.6% of the positive lymph node metastasis. All these positive nodes were limited from 10 cm proximal to 5 cm distal to the tumor. In the central direction, the rate of mesenteric lymphatic metastasis was 20.4%, and the rate of lymphatic metastasis at the root of mesentery was 4.5%, which accounted for 38.1% of the positive lymph node metastasis. Compared to the bowel axial direction, mesenteric lymphatic metastasis in the central direction was more common and should be carefully disseted during radical operation.

Absorption, tissue distribution and in vivo stability in rats of a hybrid antisense oligonucleotide following oral administration

In vivo stability and oral bioavailability of an oligodeoxynucleotide phosphorothioate containing segments of 2'-O-methyloligoribonucleotide phosphorothioates at both the 3'- and 5'-ends (hybrid oligonucleotide) were studied. A 25-mer 35S-labeled hybrid oligonucleotide was administered to rats by gavage at a dose of 50 mg/kg body weight. HPLC analysis revealed that this hybrid oligonucleotide was stable in the gastrointestinal tract for up to 6 hr following oral administration. Radioactivity associated with the hybrid oligonucleotide was detectable in portal venous plasma, systemic plasma, various tissues, and urine. Intact hybrid oligonucleotide was detected, by HPLC analysis, in portal venous plasma, systemic plasma, and various tissues. The majority of the radioactivity in urine was associated with degradative products with lower molecular weights, but the intact form was also detected. In summary, the hybrid oligonucleotide was absorbed intact through the gastrointestinal tract, indicating the possibility of oral administration of oligonucleotides, a finding that may be important in the development of antisense oligonucleotides as therapeutic agents.

In vivo stability, disposition and metabolism of a "hybrid" oligonucleotide phosphorothioate in rats

Oligodeoxynucleotide phosphorothioates containing segments of 2'-O-methyloligoribonucleotide phosphorothioates at both 3'- and 5'-ends (hybrid oligonucleotide) have been shown to be potent antisense agents. In the present study, in vivo biostability, disposition, and excretion of a 25-mer hybrid oligonucleotide were determined in rats after i.v. bolus administration of the 35S-labeled oligonucleotide at a dose of 30 mg/kg. The plasma disappearance curve for the hybrid oligonucleotide could be described by a two-compartmental model, with half-lives of 0.34 and 52.02 hr, respectively. The majority of the radioactivity in plasma was associated with the intact hybrid oligonucleotide. Urinary excretion represented the major pathway of elimination, with 21.98 +/- 3.21% (mean +/- SD) of the administered dose excreted within 24 hr and 38.13 +/- 2.99% over 240 hr post-dosing. The majority of the radioactivity in urine was associated with the degradative products with lower molecular weights, but the intact form was also detected by HPLC analysis. Fecal excretion was a minor pathway of elimination with 2.34 +/- 0.13% of the administered dose excreted over 24 hr and 6.74 +/- 0.40% over 240 hr post-dosing. A wide tissue distribution of hybrid oligonucleotide was observed based on radioactivity levels, and analysis by HPLC showed that the majority of the radioactivity in tissues was associated with the intact hybrid oligonucleotide. Further analyses of the experimental data provided a comprehensive pharmacokinetic analysis of hybrid oligonucleotide in each tissue. Compared with a previously examined oligodeoxynucleotide phosphorothioate (GEM 91) that has a similar nucleotide sequence, the hybrid oligonucleotide had a shorter distribution half-life and a longer elimination half-life, based on the quantitation of radioactivity in plasma. Although it had a similar tissue distribution pattern compared with other oligonucleotide phosphorothioates such as GEM 91, the hybrid oligonucleotide was more stable in vivo, which may be important in the development of antisense oligonucleotides as therapeutic agents.

[Pulmonary function detection in newborn infants]

We studied 120 full-term newborn infants and 20 pre-term infants by means of recording tidal breathing flow volume loops, passive flow volume technique and open circuit N2 washout technique. In the preterm infants, ventilatory function, FRC and Crs were lower than those in full-term infants, and Rrs were higher than those of full-term infants. TV, MV and PTEF were positively corelated with age (day), weight and height FRC, Crs and Trs were positively corelated with weight and height. TBFV loop in normal newborn infants did not show round or ellipse curve. The curve of expiration rose quickly, the position of expiration peak closed to the front, and decending line of expiration was relatively tilting. RR, Ti/Ttot, VPF, TPF, PF25, PTEF/TV, ME/MI, FRCkg, Crskg, sCrs, Rrs and sRrs were valuble indices in neonatal pulmonary function test. The results of our study are important in the establishment of normal values of pulmonary function indices for newborn infants in China.

Lymphocyte apoptosis during the silencing of the immune response to acute viral infections in normal, lpr, and Bcl-2-transgenic mice

This report examines the mechanisms involved in the down-regulation of the immune response in acute viral infection and documents the presence of apoptotic lymphocytes in situ in the spleens of mice during the resolution of the immune response to acute lymphocytic choriomeningitis virus infection. Apoptotic cells were detected by an in situ nucleotidyl transferase assay. Both T and B lymphocytes were shown to be dying in vivo, the latter in clusters. A biphasic occurrence of apoptosis during the course of the acute infection was observed, with elevated levels occurring at day 3 after infection and a second more pronounced peak at day 11 after infection, coincident with the decline of the cytotoxic T lymphocyte response and with the decrease in total splenic leukocyte number. Apoptosis in vivo was detected in lpr mice, suggesting that Fas expression is not imperative for lymphocyte apoptosis in the context of an acute viral infection. Apoptosis in situ and the decline of the T lymphocyte response to acute lymphocytic choriomeningitis virus infection was unaffected by the enforced lymphocyte-directed expression of Bcl-2, a protein that blocks growth factor deprivation-induced apoptosis of lymphocytes in vitro. These results argue that the silencing of the T cell response to acute infection may not be a result simply of growth factor deprivation. The susceptibility of activated T cells to apoptotic death, which has previously been associated with virus-induced immune deficiency, may therefore also explain the en masse elimination of the expanded lymphocyte pool subsequent to an acute viral infection.

Pharmacokinetics of an anti-human immunodeficiency virus antisense oligodeoxynucleotide phosphorothioate (GEM 91) in HIV-infected subjects

Human pharmacokinetics of an antisense oligodeoxynucleotide phosphorothioate (GEM 91) developed as an anti-human immunodeficiency virus (HIV) agent was carried out in this study. 35S-Labeled GEM 91 was administered to six HIV-infected individuals by means of 2-hour intravenous infusions at a dose of 0.1 mg/kg. Plasma disappearance curves for GEM 91-derived radioactivity could be described by the sum of two exponentials, with half-life values of 0.18 +/- 0.04 and 26.71 +/- 1.67 hours. The radioactivity in plasma was further evaluated by polyacrylamide gel electrophoresis, showing the presence of both intact GEM 91 and lower molecular weight metabolites. Urinary excretion represented the major pathway of elimination, with 49.15% +/- 6.80% of the administered dose excreted within 24 hours and 70.37% +/- 6.72% over 96 hours after dosing. The radioactivity in urine was associated with lower molecular weight metabolites. No drug-related toxicity was observed.

[The change of gut barrier function and gene expression after surgical stress and parenteral nutrition]

Surgical stress and parenteral nutrition (PN) may cause gut mucosal atrophy and alter barrier function. Gene expression of growth factors and enzymes in small intestine may change. The effects of alanyl-glutamine dipeptide (Ala-Gln) on gut barrier and the gene expression of insulin-like factor I (IGF-I) and glutaminase in parenteral infusion rats with massive small intestine resection were investigated. Twenty Wistar rats were catheterized with 60% small bowel resectin. They were divided into two groups. Control group (n = 10) received traditional parenteral nutritional solution, and study group (n = 10) received Ala-Gln enriched nutritional solution (3% Ala-Gln). The rats were maintained with their respective diets for 7 days. The rats in the study group maintained serum glutamine concentration (844.0 +/- 13.2uMol: 640.4 +/- 17.2uMol, P < 0.05), mucosal architecture (mucosal thickness 591 +/- 12uM: 486 +/- 8uM, P < 0.05) and villus height (404 +/- 7uM: 303 +/- 5uM, P < 0.05). Bacterial translocation rate decreased in the study group (70%: 20%, P < 0.05). Ileal mucosal IGF-I mRNA and jejunal mucosal glutaminase mRNA in the study group increased twofold and threefold respectively. The results suggest that Ala-Gln may enhance gut growth and improve gut mucosa integrity and barrier function in part by means of stimulating IGF-I and glutaminase expression in surgical stress.

Antioxidant and cytotoxic tocopheryl quinones in normal and cancer cells

We found previously that [d]-alpha-tocopherol (alpha-T) and [d]-gamma-tocopherol (gamma-T) are lipid antioxidants (thiobarbituric acid test) in model systems containing arachidonic acid (AA), cumene hydroperoxide, and Fe3+ and in smooth muscle cell (SMC) cultures challenged with AA. We now show that [d]-alpha-tocopherylquinone (alpha-TQ), [d]-delta-tocopherylquinone (delta-TQ), and [d]-gamma-tocopherylquinone (gamma-TQ) are antioxidants at low concentrations and prooxidants at high concentrations in the model system. Prooxidant activity is greater with gamma-TQ than either alpha-TQ or delta-TQ. Low concentrations of alpha-TQ, delta-TQ, and gamma-TQ are also antioxidants in SMC cultures challenged with AA. Unlike alpha-TQ, partially substituted gamma-TQ and glutathione (GSH) form a Michael adduct which has been purified and characterized. We found previously that alpha-T, gamma-T, and alpha-TQ are mitogenic in SMC. We now report that both delta-TQ and gamma-TQ but not alpha-TQ show concentration-dependent cytotoxicity (changes in morphology, propidium iodide stain) in SMC cultures. Cytotoxicity is greater with gamma-TQ than delta-TQ. An acute lymphoblastic leukemia (ALL) cell line shows greater chemosensitivity (MTT and Neutral Red assays) to gamma-TQ than to either doxorubicin (DOX) or vinblastine (VLB). An ALL cell line resistant to both DOX and VLB retains the same chemosensitivity to gamma-TQ as the drug-sensitive ALL cell line. ALL cell lines are unaffected by either alpha-TQ or the GSH Michael adduct of gamma-TQ. These data show that partially substituted tocopheryl quinones capable of forming Michael adducts are potential chemotherapeutic agents for multidrug-resistant cancer cells.

In vivo stability and disposition of a self-stabilized oligodeoxynucleotide phosphorothioate in rats

The use of antisense oligonucleotides represents a novel, genetically based therapy. The biostability and pharmacokinetics of a 33-mer self-stabilized oligodeoxynucleotide with significant anti-HIV activity was determined in rats after intravenous administration of [35S]oligodeoxynucleotide. Plasma disappearance of the labeled oligodeoxynucleotide could be described by a two-compartment model, with half-lives of 0.54 and 41.44 h. The oligodeoxynucleotide in plasma remained mainly intact. Urinary excretion represented the major elimination pathway, with approximately 27% of the administered dose excreted within 24 h and 57% over 240 h. The majority of radioactivity in urine was attached to degradative products. Fecal excretion was a minor elimination pathway. A wide tissue distribution of the oligonucleotide was observed, with the majority of radioactivity in most tissues being intact. Compared with other linear oligonucleotide phosphorothioates, the self-stabilized oligonucleotide was more stable in vivo, which may be important in development of antisense oligonucleotides as therapeutic agents.

In vivo stability and disposition of a self-stabilized oligodeoxynucleotide phosphorothioate in rats

The use of antisense oligonucleotides represents a novel, genetically based therapy. The biostability and pharmacokinetics of a 33-mer self-stabilized oligodeoxynucleotide with significant anti-HIV activity was determined in rats after intravenous administration of [35S]oligodeoxynucleotide. Plasma disappearance of the labeled oligodeoxynucleotide could be described by a two-compartment model, with half-lives of 0.54 and 41.44 h. The oligodeoxynucleotide in plasma remained mainly intact. Urinary excretion represented the major elimination pathway, with approximately 27% of the administered dose excreted within 24 h and 57% over 240 h. The majority of radioactivity in urine was attached to degradative products. Fecal excretion was a minor elimination pathway. A wide tissue distribution of the oligonucleotide was observed, with the majority of radioactivity in most tissues being intact. Compared with other linear oligonucleotide phosphorothioates, the self-stabilized oligonucleotide was more stable in vivo, which may be important in development of antisense oligonucleotides as therapeutic agents.

Pharmacokinetics and tissue distribution in rats of an oligodeoxynucleotide phosphorothioate (GEM 91) developed as a therapeutic agent for human immunodeficiency virus type-1

An antisense oligodeoxynucleotide phosphorothioate, namely gene expression modulator 91 (GEM 91), has been demonstrated to have significant anti-human immunodeficiency virus activity in various tissue culture models. The present study was undertaken to determine the pharmacokinetics and tissue distribution of GEM 91 in rats following i.v. bolus administration of 35S-radiolabeled GEM 91. Plasma disappearance curves for GEM 91-derived radioactivity could be described by the sum of two exponentials, with half-lives (mean +/- SEM) of 0.95 (+/- 0.07) and 47.57 (+/- 14.48) hr. Urinary excretion represented the major pathway of elimination of GEM 91, with 26.67 +/- 6.46% (mean +/- SD) of the administered dose excreted within 24 hr and 58.12 +/- 4.36% over 240 hr after GEM 91 administration. Fecal excretion was a minor pathway of elimination of GEM 91 with 1.4 +/- 0.62% (mean +/- SD) of the administered dose excreted over 24 hr and 8.54 +/- 0.64% over 240 hr. A wide tissue distribution of GEM 91 was observed. During the initial 30 min, the highest levels of tissue radioactivity were found in the kidney, liver, spleen, lungs, and heart. Radioactivity was retained over longer time periods in the kidneys, liver, heart, and intestine. Analyses of the extracted radioactivities from plasma, kidney, and liver by gel electrophoresis showed the presence of both intact GEM 91 and degradative products with smaller molecular weights. Radioactivity in urine was found to be degradative metabolites of GEM 91. Based on the experimental data, pharmacokinetic parameters for GEM 91 in each tissue and biological fluids were calculated using computer-based two-compartmental i.v. bolus or absorption models. This study is important not only in providing the basis for future studies of GEM 91 in humans, but also in understanding the pharmacology and toxicology of antisense oligodeoxynucleotide phosphorothioates, in general.

Image-guided insertion of transpedicular screws. A laboratory set-up

STUDY DESIGN

A computer-assisted system allowing precise preoperative planning and real-time intraoperative image localization of surgical instruments is tested in a laboratory setup.

OBJECTIVES

The purpose of this study is to assess the applicability, functionality, and accuracy of this transpedicular spinal fixation technique.

SUMMARY OF BACKGROUND DATA

Most techniques in transpedicular spinal fixation rely on the identification of predefined targets with the help of anatomic landmarks and on the intraoperative use of image intensifiers. Various studies report considerable screw misplacement rates which may lead to serious clinical sequelae such as permanent nerve damage.

METHODS

The proposed system was tested in an in vitro setup drilling 20 pedicle pilot holes in lumbar vertebrae. The accuracy was assessed using precision cuts through the pedicles and simulation of a 6-mm pedicle screw insertion.

RESULTS

An ideal screw position was found in 70 of 77 cuts, and in no case was an injury to the pedicular cortex observed.

CONCLUSIONS

The presented technique provides a safe, accurate, and flexible basis for transpedicular screw placement in the spine. This approach should be further evaluated in clinical applications.

Sodium pentobarbital versus alpha-chloralose anesthesia. Experimental production of substantially different slopes in the transmural CP/ATP ratios within the left ventricle of the canine myocardium

BACKGROUND

Transmural analyses of the creatine phosphate (CP)/ATP ratio in various lamina of the canine myocardium have previously revealed significant variations in the CP/ATP ratio, with the subendocardial layer displaying a decreased ratio relative to the subepicardial layer. Without exception, these results were obtained under sodium pentobarbital anesthesia. These findings have been interpreted to imply that the normal endocardium may be operating in the oxygen-limited domain or that there are transmurally varying set points for the regulation of oxidative phosphorylation.

METHODS AND RESULTS

In this work, we examine the effect of the anesthetic regimen on the transmural CP/ATP ratio within the left ventricular wall of the canine myocardium using spatially localized 31P-nuclear magnetic resonance (NMR) and an open-chest model. Two anesthetics were compared, alpha-chloralose and sodium pentobarbital. Under sodium pentobarbital, the CP/ATP ratio ranged from 1.92 +/- 0.06 to 2.51 +/- 0.08 from endocardium to epicardium, resulting in a transmural slope in the CP/ATP ratio of 0.149 +/- 0.047 (n = 22). Under alpha-chloralose, CP/ATP ratios ranged from 2.18 +/- 0.05 to 2.32 +/- 0.06, with a transmural slope of 0.035 +/- 0.018 (n = 38). Thus, the transmural slope in CP/ATP ratio was nearly four times greater with sodium pentobarbital than with alpha-chloralose, and the difference in these slopes was statistically significant (P = .029). No difference was observed in average CP/ATP obtained from the entire wall with either anesthetic.

CONCLUSIONS

These results demonstrate that the transmural trend in CP/ATP ratio previously reported in the myocardium is likely to be a direct reflection of the sodium pentobarbital anesthetic regimen, not truly reflecting the trend in the normal unanesthetized animal. Moreover, since the transmural variation in CP/ATP ratio was greatly reduced with alpha-chloralose, it appears unlikely that the endocardium in the normal unanesthetized heart is operating in the oxygen-limited domain. These results also point to the importance of the anesthetic regimen in biochemical analysis, indicate the necessity of increased caution in directly translating results obtained under anesthesia, and demonstrate the unique power of in vivo NMR to extract such subtle biochemical information.