The use of computed tomography-guided stereotactic techniques in the treatment of brain stem abscesses

A case of a brain stem abscess that was successfully treated using CT guided stereotaxy together with antibiotic therapy is presented. The literature is reviewed and the role of stereotaxy in the treatment of brain stem abscess is discussed.     

Characterization of in vitro metabolites of the aryl hydrocarbon receptor ligand 6-formylindolo[3,2-b]carbazole by liquid chromatography-mass spectrometry and NMR.

The tryptophan photoproduct 6-formylindolo[3,2-b]carbazole (FICZ) exhibits the highest aryl hydrocarbon receptor (AhR) binding affinity reported so far. In different cells, in vitro, both extracts of UV-irradiated tryptophan and the synthesized pure compound FICZ induce a rapid and transient expression of AhR-regulated genes. The transient induction suggests that the biotransformation gene battery induced by AhR activation takes part in a metabolic degradation of the ligand, whereby a low steady-state level is regained. The down-regulation of AhR-regulated gene expression was previously shown to be dependent on cytochrome P450 1A1 (CYP1A1). Metabolism of FICZ generates five major metabolites, which appeared as three peaks (M1-M3) in the high performance liquid chromatography. The aim of the present study was to use rat liver S9 from Aroclor-pretreated rats to produce large enough quantities of FICZ metabolites for structure characterization and to determine their product precursor relationship. NMR analysis of large combined fractions of the metabolites indicated that M3 and M2 contained 2 isomers, respectively. By means of liquid chromatography-mass spectrometry (negative ion electrospray mode) and NMR spectroscopy (by (1)H-NMR, correlation spectroscopy, and nuclear Overhauser effect spectroscopy techniques) five metabolites of FICZ were identified, and their structures were elucidated. The molecular weights of the two M3 isomers were 300 and both M2 and M1 compounds demonstrated molecular weights of 316, corresponding to addition of one (M3) and of two oxygen (M2 and M1), respectively. The structures were assigned as 2- and 8-hydroxy (M3), 2,10- and 4,8-dihydroxy (M2) and 2,8-dihydroxy derivatives of indolo[3,2-b]carbazole-6-carboxaldehyde (6-formylindolo[3,2-b]carbazole).     

Combining chondrocytes and smooth muscle cells to engineer hybrid soft tissue constructs

Engineering new tissues using cell transplantation may provide a valuable tool for reconstructive surgery applications. Chondrocyte transplantation in particular has been successfully used to engineer new tissue masses due to the low metabolic requirements of these cells. However, the engineered cartilaginous tissue is too rigid for many soft tissue applications. We propose that hybrid tissue engineered from chondrocytes and smooth muscle cells could reflect mechanical properties intermediate between these two cell types. In this study, rat aortic smooth muscle cells and pig auricular chondrocytes were co-cultured on polyglycolic acid fiber-based matrices to address this hypothesis. Mixed cell suspensions were seeded by agitating the polymer matrices and a cell suspension with an orbital shaker. After seeding, cell-polymer constructs were cultured in stirred bioreactors for 8 weeks. The cell density and extracellular matrix (collagen, elastin, and glycosaminoglycan) content of the engineered tissues were determined biochemically. After 8 weeks in culture, the hybrid tissue had a high cell density (5.8 x 108 cells/cm(3)), and elastin (519 microg/g wet tissue sample), collagen (272 microg/g wet tissue sample), and glycosaminoglycan (GAG; 10 microg/g wet tissue sample) content. Mechanical testing indicated the compressive modulus of the hybrid tissues after 8 weeks to be 40.8 +/- 4.1 kPa and the equilibrium compressive modulus to be 8.4 +/- 0.8 kPa. Thus, these hybrid tissues exhibited intermediate stiffness; they were less stiff than native cartilage but stiffer than native smooth muscle tissue. This tissue engineering approach may be useful to engineer tissues for a variety of reconstructive surgery applications.     

Permanent low-activity iodine-125 implants for cerebral metastases

Beginning in 1987, selected patients with metastatic braintumors were treated with permanent implants of low-activityradioactive iodine-125 (¹²⁵I) seeds. These patients underwent craniotomy,gross total resection of the metastatic lesion, andplacement of the seeds. In general, criteria fortreatment included the presence of a recurrent tumorwith a volume too large to permit radiosurgery,and a Karnofsky Performance Score of 70 orhigher. Thirteen patients underwent 14 implant procedures; allreceived external whole-brain radiotherapy. Implant dose ranged from43 Gy to 132 Gy, with a meanof 83 Gy. Survival after implantation ranged from2 weeks to almost 9 years, with amedian of 9 months. Clinical and radiographic localcontrol was obtained in 9 patients. Two patientsdied of acute, postoperative complications within a monthof implantation, so no information regarding tumor controlis available for them. Late complications included abone flap infection in one patient and aCSF leak in another; both were treated withoutfurther sequelae.These results demonstrate that permanent ¹²⁵I implants canresult in good survival and quality of life,and occasionally can yield long-term survival. Potentially, itis a cost-effective treatment in that a separateprocedure for stereotactic implantation or radiosurgery is notneeded, as is the case with the useof temporary high-activity seeds. The permanent implantation itselfadds less than 10 minutes to the craniotomy,and the risk of symptomatic radiation necrosis islow. We recommend consideration of this procedure inpatients harboring large, recurrent metastatic tumors that requirefurther surgery.     

Slow Infusion of Low‐dose Ketamine Reduces Bothersome Side Effects Compared to Intravenous Push: A Double‐blind,Double‐dummy,Randomized Controlled Trial

Objective

We compared the analgesic efficacy and incidence of side effects when low‐dose (0.3 mg/kg) ketamine (LDK) is administered as a slow infusion (SI) over 15 minutes versus an intravenous push (IVP) over 1 minute.

Methods

This was a prospective, randomized, double‐blind, double‐dummy, placebo‐controlled trial of adult ED patients presenting with moderate to severe pain (numerical rating scale [NRS] score ≥ 5). Patients received 0.3 mg/kg ketamine administered either as a SI or a IVP. Our primary outcome was the proportion of patients experiencing any psychoperceptual side effect over 60 minutes. A secondary outcome was incidence of moderate or greater psychoperceptual side effects. Additional outcomes included reduction in pain NRS scores at 60 minutes and percent maximum summed pain intensity difference (%SPID).

Results

Fifty‐nine participants completed the study. A total of 86.2% of the IVP arm and 70.0% of the SI arm experienced any side effect (difference = 16.2%, 95% confidence interval [CI] = –5.4 to 37.8). We found a large reduction in moderate or greater psychoperceptual side effects with SI administration—75.9% reported moderate or greater side effects versus 43.4% in the SI arm (difference = 32.5%, 95% CI = 7.9 to 57.1). Additionally, the IVP arm experienced more hallucinations (n = 8, 27.6%) than the SI arm (SI n = 2, 6.7%, difference = 20.9%, 95% CI = 1.8 to 43.4). We found no significant differences in analgesic efficacy. At 60 minutes, the mean %SPID values in the IVP and SI arms were 39.9 and 33.5%, respectively, with a difference of 6.5% (95% CI = –5.8 to 18.7).

Conclusion

Most patients who are administered LDK experience a psychoperceptual side effect regardless of administration via SI or IVP. However, patients receiving LDK as a SI reported significantly fewer moderate or greater psychoperceptual side effects and hallucinations with equivalent analgesia.

     

Sensitivity and Specificity of Standard and Rapid HIV-Antibody Tests Evaluated by Seroconversion and Non-Seroconversion Low-Titre Panels

Background and objectives: The aim of this study is to compare the relative sensitivity and specificity of commercial HIV-antibody assays using seroconversion, non-seroconversion panels, and negative blood donor samples. Materials and methods: We evaluated the sensitivity of five standard ELISA HIV-antibody assays: Vironostika HIV Uni-Form II, Abbott recombinant HIV-1/HIV-2 third-generation EIA, Biotest Anti-HIV-1/-2 recombinant, Recombigen HIV-1/HIV-2 EIA and Wellcozyme HIV 1+2 (VK54/55), and three rapid screening tests, Capillus HIV-1/HIV-2, Abbott Test Pack HIV-1/HIV-2 third-generation EIA, and Sensy-Test HIV 1/2. All tests were assessed using four panels of plasma samples obtained from individuals who were seroconverting and a low-titre HIV-antibody panel of samples. Specificity of the standard screening tests was determined on 3,500 HIV-antibody-negative blood donor samples. Results: There was no statistically significant difference in sensitivity between the five standard ELISA tests. One of these tests was significantly less specific than the others. The standard ELISA tests detected all the low-titre HIV-antibody-positive samples. Two of the rapid screening tests were significantly less sensitive on the seroconversion panels and all three tests failed to detect at least one of the positive samples in the low-titre panel. Conclusions: The additional risk of using one or other of the standard ELISA tests under review of not detecting all HIV-positive units of blood is not statistically significant. Using some of the rapid screening tests will, however, add a significant additional risk. A rapid screening test should therefore be adopted only after careful consideration of the effect of a possible lack of sensitivity on the safety of the blood supply.