Computer-aided navigation in neurosurgery

The article comprises three main parts: a historical review on navigation, the mathematical basics for calculation and the clinical applications of navigation devices. Main historical steps are described from the first idea till the realisation of the frame-based and frameless navigation devices including robots. In particular the idea of robots can be traced back to the Iliad of Homer, the first testimony of European literature over 2500 years ago. In the second part the mathematical calculation of the mapping between the navigation and the image space is demonstrated, including different registration modalities and error estimations. The error of the navigation has to be divided into the technical error of the device calculating its own position in space, the registration error due to inaccuracies in the calculation of the transformation matrix between the navigation and the image space, and the application error caused additionally by anatomical shift of the brain structures during operation. In the third part the main clinical fields of application in modern neurosurgery are demonstrated, such as localisation of small intracranial lesions, skull-base surgery, intracerebral biopsies, intracranial endoscopy, functional neurosurgery and spinal navigation. At the end of the article some possible objections to navigation-aided surgery are discussed.

Reversible and irreversible inhibitory activity of succinic and maleic acid derivatives on acetylcholinesterase

Aryl succinic and maleic acid derivatives are potent inhibitors of bovine acetylcholinesterase in vitro. Succinic acid aminophenol derivatives 1b-e and 2b-d act as reversible inhibitors of acetylcholinesterase, while maleic acid aminophenol derivatives 3b-d and 4c-e act as choline subsite-directed irreversible inhibitors, detected by dialysis in the presence of edrophonium. Linear relationships between the logarithm of the velocity of hydrolysis of acetylcholine plotted against the time of incubation at several different inhibitor concentrations were determined. The K(i) for reversible competitive inhibitors was determined. For irreversible inhibitors the K(i) for the dissociation constant of the enzyme-inhibitor complex at the beginning of the recognition process was also determined as well as the inactivation constant of the enzyme-inhibitor adduct formation k(+2) and the bimolecular inhibition constant k(i) for the inhibition of acetylcholinesterase by aminophenol derivatives 3b-d and 4c-e. The conclusions of this study can be summarized as follows for both families: (a) the aromatic moiety played a critical role in the recognition of the active site; (b) in case of the reversible inhibitor, when the ester function took the place of the hydroxyl fragment, there was an important increase in the affinity; and (c) the distance between phenolic hydroxyl and nitrogen was critical because the inhibition is ortho<<meta<para.

Stereotactic biopsies guided by an optical navigation system: technique and clinical experience

Frame-based stereotactic biopsies are time-consuming procedures making necessary head fixation in a ring, explicit coordinate calculation and setting of the parameters. Frameless systems make many of these intermediate steps unnecessary, impose less mechanical restrictions regarding access to the lesions, and with slight modifications can be used to perform stereotactic biopsies. A special adaptation designed to fix the holder and the biopsy instrument is described. The neuronavigation optical tracking system of Radionics was used. CT scans were performed with 6 skin markers. Calibration was performed after head fixation in the Mayfield clamp. Mean calibration error was 2.19 +/- 0.81 mm. The light-emitting diode holder of the pointer was fixed into 2 Leila arms and moved under visual control based on CT images. The target point was selected, Leila arms fixed and a burr hole performed. The cannula was introduced to the target, being fitted with a depth stop in a length identical to that of the pointer on the screen. If necessary a second trajectory was easily selected. 49 patients underwent a frameless stereotactic biopsy. All targets except seven were superficial or in the white matter. In selected cases the biopsies were taken from deep-seated lesions. A histological diagnosis was obtained in 100 % of the cases. Four cases deteriorated postoperatively, two of these related to intratumoral bleeding. Navigation is a simple and effective method to perform biopsies of superficial and relatively large lesions. Frame-based procedures are restricted to brainstem tumors and lesions less than 1.5 cm in diameter.

Culture and regeneration of human neurons after brain surgery

Cortical human brain tissue was obtained from 11 craniotomies for intractable epilepsy or tumor resection. Neuregen transport medium preserved viability at 4 degrees C during transfer to the culture laboratory. Cells were isolated and cultured by methods previously developed for adult rat neurons (Brewer GJ. Isolation and culture of adult rat hippocampal neurons. J. Neurosci. Meth. 1997:71:143-55). In about 40% of the cases, cultures regenerated with a majority of neuron-like cells that stained for neurofilament and not GFAP. After 3 weeks of culture from a 70 year old meningioma case, synapse-like structures were revealed by electron microscopy. Trophic support from basic human recombinant fibroblast growth factor was synergistically improved with the steroid hormone dehydroepiandrosterone 3-sulfate. Another 40% of the cases resulted in cultures that were predominantly GFAP positive astroglia. The remaining 20% of the cases did not regenerate cells with neuron-like or glial processes. Three postmortem cases did not regenerate neurites. These methods may aid development of human culture models of epilepsy as well as human pharmacology, toxicology and development of improved methods for brain grafts.

Gemcitabine plus vinorelbine in nonsmall cell lung carcinoma patients age 70 years or older or patients who cannot receive cisplatin. Oncopaz Cooperative Group

BACKGROUND

Although the prevalence of nonsmall cell lung carcinoma (NSCLC) is high among elderly patients, few data are available regarding the efficacy and toxicity of chemotherapy in this group of patients. Recent reports indicate that single agent therapy with vinorelbine (VNB) or gemcitabine (GEM) may obtain a response rate of 20-30% in elderly patients, with acceptable toxicity and improvement in symptoms and quality of life. In the current study the efficacy and toxicity of the combination of GEM and VNB in elderly patients with advanced NSCLC or those with some contraindication to receiving cisplatin were assessed.

METHODS

Forty-nine patients with advanced NSCLC were included, 38 of whom were age >/= 70 years and 11 were age < 70 years but who had some contraindication to receiving cisplatin. All patients were evaluable for response and toxicity. Treatment was comprised of VNB, 25 mg/m(2), plus GEM, 1000 mg/m(2), both on Days 1, 8, and 15 every 28 days. Patients received a minimum of three courses unless progressive disease was detected.

RESULTS

One hundred sixty-five courses were administered, with a median of 3. 6 courses per patient. The overall response rate was 26% (95% confidence interval, 15-41%). Two patients attained a complete response (4%) and 11 patients (22%) achieved a partial response. Eastern Cooperative Oncology Group performance status improved in 35% of those patients with an initial value > 0, whereas relief of at least 1 symptom without worsening of other symptoms was noted in 27 patients (55%). The median time to progression was 16 weeks and the 1-year survival rate was 33%. Toxicity was mild. Six patients (12%) had World Health Organization Grade 3-4 neutropenia, 2 patients (4%) had Grade 3-4 thrombocytopenia, and 2 patients (4%) had Grade 3 neurotoxicity. Three patients with severe neutropenia (6%) died of sepsis. The median age of those patients developing Grade 3-4 neutropenia was significantly higher than that of the remaining patients (75 years vs. 72 years; P = 0.047).

CONCLUSIONS

The combination of GEM and VNB is moderately active and well tolerated except in patients age >/= 75 years. This age group had an increased risk of myelosuppression. Therefore the prophylactic use of granulocyte-colony stimulating factor should be considered with this treatment. New chemotherapy combinations with higher activity and lower toxicity are needed for elderly patients with advanced NSCLC.

Sarcoptic mange in Spanish ibex from Spain

The Spanish ibex (Capra pyrenaica hispanica) population of the "Sierras de Cazorla, Segura y Las Villas" Nature Park (Spain) was isolated as the result of a severe epidemic of sarcoptic mange. In this context, the dynamic characteristics of the disease were analyzed in a wild group consisting of 35 animals from the beginning of the epizootic (when the mating period started) to the extinction of the population due to mange. Monthly tracking permitted the sequential characterization of the pathology in each animal. The duration of the disease was 2 to 3 mo, evolving to severe disease and terminating in death. Incidence and prevalence rates in terms of morbidity and severity, and mortality and lethality were calculated. At the end of the mating season, 81% of the population were affected. There were no statistically significant differences in severity of the disease across sex or age categories of the animals. Most of the carcasses were found in caves used as refuge and/or near rivers or streams. Additionally, 46 of the 63 (73%) ibex captured in different areas of the nature park were naturally infected with the Sarcoptes scabiei. Infected ibex were examined for number of mites during the initial stage of the disease (n = 3), in the development stage (n = 12), in the consolidation stage (n = 17), and in the chronic stage (n = 14). The prevalence of mites in different anatomical regions was determined in each of these phases of the infection. A histological study of the skin lesions was conducted in 22 animals. Both the clinical and the pathological (macroscopic and microscopic) aspects of the sarcoptic mange in Spanish ibex corresponded to the classic description of sarcoptic mange in other wild and domestic small ruminants.

Factors from Trypanosoma cruzi interacting with AP-1 sequences

Interaction between factors from Trypanosoma cruzi extracts and AP-1 sequences was studied by electrophoretic mobility shift assays. Using a double-stranded probe carrying the AP-1 sequence from the SV40 promoter, three specific complexes designated A, B, and C were detected. Complexes A and C were formed when using single-stranded probes. The relative amount of complex B, specific for double-stranded DNA, increased as a function of probe length. Complexes were stabilized by cross-linking with UVC irradiation and resolved on denaturing SDS-PAGE. Complex A generated bands of 60- and 39 kDa; complex B produced two bands of 46- and 43 kDa; and complex C generated one band of 43 kDa. The AP-1 binding activity was much higher in purified nuclear preparations than in soluble fractions, and was detected in crude extracts from the three forms of the parasite. The binding signal, however, was much stronger in amastigote and trypomastigote than in the epimastigote forms. Specific binding was increased by oxidative stress. Antibodies raised against peptides corresponding to conserved domains of mammalian c-Jun and c-Fos detected bands of 40- and 60 kDa, respectively, in a nuclear epimastigote preparation.

A comparative trial of two modalities of speech intervention for compensatory articulation in cleft palate children, phonologic approach versus articulatory approach

To compare two modalities of speech intervention (SI) in cleft palate children with compensatory articulation disorder (CAD). The first modality was a phonologic based intervention, the second modality was an articulatory or phonetic intervention. The main purpose is to study whether a phonologic intervention may reduce the total time of speech therapy necessary for correcting CAD in cleft palate children as compared to an articulatory intervention. A prospective, comparative, and randomized trial was carried out. Cleft palate children with velopharyngeal insufficiency and CAD were included in the study group. Only patients with an age ranging from 3 to 7 years were included. A total of 29 patients were selected and were divided randomly into two groups. Fifteen patients were included in the first group (control) and received articulatory SI. Fourteen patients were included in the second group (active) and received phonologic SI. The speech pathologist in charge of the SI was the same in all cases. A blind procedure was utilized whereby each patient was evaluated independently by two speech pathologist every three months until both examiners were convinced that CAD had been completely corrected. The mean total time of SI required for the normalization of speech in the two groups of patients was compared. Median age in the control group was 54 months, and 55.50 months in the active group (P > 0.05). The mean total time of SI in the control group was 30.07, and 14.50 in the active group. A Student's t-test demonstrated that the total time of SI was significantly reduced (P < 0.001) when a phonological intervention was utilized. Phonologic based SI significantly reduced the time necessary for correcting CAD in cleft palate children.

Revision and removal of stimulating electrodes following long-term therapy with the vagus nerve stimulator

BACKGROUND

A significant concern about vagus nerve stimulation therapy has been the disposition of the spiral stimulating electrodes once treatment is considered ineffective or is no longer desired. Because the electrodes are wrapped around the vagus nerve, there is the potential for nerve injury during their removal.

METHODS

We attempted removal of the spiral stimulating electrodes from 10 patients who received long-term vagus nerve stimulation therapy for drug-resistant epilepsy. In some patients, replacement with electrodes was also performed for poorly functioning leads.

RESULTS

The mean duration of electrode implantation was 3.7+/-2.2 years (range 1.1-7.3 years). In seven patients, the old electrodes were removed completely from the nerve. No adverse events occurred intraoperatively or postoperatively.

CONCLUSIONS

Our results indicate that the spiral electrodes may be safely removed from the vagus nerve, even after the electrodes have been implanted for several years. The reversibility of lead implantation may enhance the attractiveness of vagus nerve stimulation therapy for patients with medically-intractable epilepsy.

Analysis of the in vivo nitrosation capacity of the larvae used in the wing somatic mutation and recombination test of Drosophila melanogaster

The in vivo nitrosation capacity of third-instar larvae of Drosophila melanogaster was assessed using the wing somatic mutation and recombination test (SMART). Larvate derived from two different crosses, the standard cross (ST) and the high bioactivation cross (HB) both involving the recessive wing cell markers multiple wing hairs (mwh) and flare (flr3), were used. The HB cross is characterised by an increased cytochrome P450-dependent bioactivation capacity for promutagens and procarcinogens. The larvae were treated either with methyl urea, sodium nitrite or its combination. N-Nitrosomethylurea was used as a positive control. The wings of the resulting flies were analysed for the occurrence of mutant spots produced by various types of mutational events or by mitotic recombination. Methyl urea is negative in the ST and the HB cross, whereas sodium nitrite is weakly genotoxic in both crosses. However, the combination of both compounds produces highly increased frequencies of mutations and recombinations predominantly in the HB cross. The genotoxic effects produced by the combined treatments were considerably increased when mashed potatoes or an agar-yeast medium were used for the treatment instead of the standard instant medium. Treatment of larvae with the mixture resulting from the in vitro reaction of nitrosation precursors also resulted in high frequencies of induced spots comparable to those recorded with the potent genotoxin N-nitrosomethylurea. Further experiments showed that the genotoxic effect resulting from the in vivo exposure to nitrosation precursors can be reduced by co-treatment with catechin, a known nitrosation inhibitor. The present study demonstrates that the wing spot test is well suited for the determination of genotoxicity produced by in vivo nitrosation processes and for the study of their modulation by individual compounds or dietary complex mixtures.

Severe limb deficiencies, vertebral hypersegmentation, and mirror polydactyly: two additional cases that expand the phenotype to a more generalized effect on blastogenesis

We report on 2 unrelated fetuses with a multiple congenital anomaly pattern of severe limb deficiencies, vertebral/rib alterations, and mirror polydactyly similar to that described previously by us [Urioste et al., Hum Genet 97:214-217, 1996]. In addition, the two cases we present here have a more extense alteration of blastogenesis, expanding the phenotype of the cases previously reported. We have suggested [Urioste et al., Hum Genet 97:214-217, 1996] that this condition may be caused by a mutation in a developmental control gene that affects body-plan organization. The minimal estimate of the prevalence of this new entity in our population (the Spanish Collaborative Study of Congenital Malformations, ECEMC) is 3.0/ 1,000,000 live births.

Uracil and tegafur modulated with leucovorin: an effective regimen with low toxicity for the treatment of colorectal carcinoma in the elderly. Oncopaz Cooperative Group

BACKGROUND

In spite of the high prevalence of cancer in the elderly, little information is available about the efficacy and toxicity of chemotherapy in elderly patients. In a previous study, the authors demonstrated that the combination of uracil and tegafur (UFT) with leucovorin (LV) was active and well tolerated in patients with advanced colorectal carcinoma (ACC). The objective of the current study was to determine the efficacy and toxicity of this regimen in elderly patients with ACC.

METHODS

Thirty-eight unselected patients older than 70 years (median age, 74 years) with measurable ACC were included. All patients were evaluable for toxicity and response. The regimen consisted of intravenous LV 500 mg/m2 on Day 1, oral LV 15 mg every 12 hours on Days 2-14, and oral UFT 390 mg/m2 on Days 1-14. Treatment was repeated every 28 days for a minimum of 4 courses per patient.

RESULTS

Two hundred eighty-eight cycles of chemotherapy were delivered (median, 7 per patient). Two patients (5%) achieved a complete response and 9 (24%) a partial response, for an overall response rate of 29%. Toxicity was mild, without dose-limiting myelosuppression. Four patients (10%) experienced Grade 3-4 diarrhea, 1 patient had Grade 3-4 nausea/vomiting, and 1 had Grade 3-4 mucositis. Grade 3-4 toxicity was more frequent among women than men (38% vs. 4%, P < 0.05).

CONCLUSIONS

Treatment with oral UFT modulated with LV is effective, well tolerated, and feasible on an outpatient basis for elderly patients with ACC. However, elderly women should be followed closely for the early detection of toxicity.

Control of Trypanosoma cruzi epimastigote motility through the nitric oxide pathway

Trypanosoma cruzi epimastigote motility can be enhanced by addition of L-arginine, to the culture. This effect is blocked by N-methyl-L-arginine, a competitive inhibitor of the nitric oxide synthase. N-methyl-D-aspartate and L-glutamate, two agonists of the NMDA/L-glutamate receptor, also enhanced motility. This stimulation is blocked by MK-801 a noncompetitive antagonist of the NMDA receptor. In addition, sodium nitroprusside, a guanylyl cyclase stimulator and 8-Br-cyclic GMP, and analog of cyclic GMP, also stimulated epimastigote motility. It is suggested that an increase of intracellular cyclic GMP levels mediated by nitric oxide may be responsible for the increase in epimastigote motility.

UFT modulated with leucovorin in advanced colorectal cancer: Oncopaz experience

A phase II trial of UFT (Tegafur and Uracil) modulated by leucovorin was undertaken by the Oncopaz Cooperative Group to assess the efficacy and toxicity of this combination in patients with advanced colorectal cancer. A total of 75 patients were given 500 mg/m2 intravenous leucovorin and 195 mg/m2 of oral UFT on day 1, followed by oral leucovorin 15 mg/12 h and 195 mg/m2/12 h of oral UFT on days 2-14. An overall response rate of 39% was obtained, with seven complete responses (9%), and 22 partial responses (29%). The primary toxicity was gastrointestinal, with grade 1-2 diarrhea occurring in 8.5% of courses, and grade 3-4 in 3.5%. Hematologic toxicity was minimal, and there were no deaths due to toxicity. This regimen was active and well tolerated in patients with advanced colorectal cancer, including those 70 years of age or older.

[Treatment of the herniated lumbar disk. Presentation of 182 operated patients]

We have reviewed the signs and symptoms of a herniated lumbar disc and the indications for medical an/or surgical treatment. We have also considered the different surgical options. The author presents his own statistics: 182 patients operated (210 surgical Interventions); in 167 patients (91.8%) the herniated disc was in the L4-5, L5-S1 space or in both, in eight (4.4%) in L3-4, in seven (3.8%) in L2-3 and L3-4.

Treatment of metastatic malignant melanoma with cisplatin plus tamoxifen

A phase II study was performed to assess the efficacy and toxicity of the combination of cisplatin (CDDP) and tamoxifen (TAM) in patients with metastatic malignant melanoma (MM). A total of 31 consecutive previously untreated patients with unresectable measurable MM were given 100 mg/m2 CDDP every 21 days and 60 mg TAM every 12 h daily. All courses were given on an outpatient basis. A total of 119 courses of treatment were given. In all, 5 of the 31 patients (16%) had an objective response (95% confidence interval 5.3-34%) and 2 (6%) achieved a clinical complete response. The median duration of response was 7 months. The main side effect was gastrointestinal: 13% of the patients experienced grade 3/4 nausea/vomiting. Hematological or neurological toxicities were mild and rare. In conclusion, the combination CDDP-TAM has limited activity in MM, although its toxicity is tolerable. Our results do not allow us to recommend its use for the treatment of MM.

Cisplatin and UFT modulated with leucovorin for the treatment of Advanced non-small-cell lung cancer

We performed a phase II study to assess the efficacy and toxicity of the cisplatin-UFT-leucovorin (LV) combination in patients with advanced non-small-cell lung cancer (NSCLC). Twenty-five patients with measurable disease who had not received prior chemotherapy were entered into the trial. The therapeutic regimen consisted of cisplatin 90 mg/m(2) and i.v. LV 500 mg/m(2) on day 1, followed by oral UFT 390 mg/m(2)/day (in two doses on days 1 through 14. Patients also received oral LV 15 mg/12 h on days 2 through 14. Seventeen patients required reduced doses of UFT (200 mg/m(2) due to toxicity. Courses were repeated every 28 days for a minimum of three per patient. Three of 25 patients (12%) achieved a partial response (95% CI: 2.6 to 32.2%), two with 390 mg/m(2)/day and one with 200 mg/m(2)/day of UFT. The main side effects were hematological and gastrointestinal. In the courses including 390 mg/m(2)/day of UFT, grade 3-4 toxicity was leucopenia in 18% of the courses, nausea/vomiting in 27%, and diarrhea and epigastralgia in 13% each. Grade 3-4 toxicities for 200 mg/m(2)/day of UFT were leucopenia 2%, nausea/vomiting 9% and diarrhea 7%. In conclusion, this regimen cannot be recommend for the treatment of advanced NSCLC due to its low response rate and high toxicity.

The nitric oxide transduction pathway in Trypanosoma cruzi

A nitric oxide synthase was partially purified from soluble extracts of Trypanosoma cruzi epimastigote forms. The conversion of L-arginine to citrulline by this enzyme activity required NADPH and was blocked by EGTA. The reaction was activated by Ca2+, calmodulin, tetrahydrobiopterin, and FAD, and inhibited by N omega-methyl-L-arginine. L-Glutamate and N-methyl-D-aspartate stimulated in vivo conversion of L-arginine to citrulline by epimastigote cells. These stimulations could be blocked by EGTA, MK-801, and ketamine and enhanced by glycine. A sodium nitroprusside-activated guanylyl cyclase activity was detected in cell-free, soluble preparations of T. cruzi epimastigotes. L-Glutamate, N-methyl-D-aspartate, and sodium nitroprusside increased epimastigote cyclic GMP levels. MK-801 bound specifically to T. cruzi epimastigote cells. This binding was competed by ketamine and enhanced by glycine or L-serine. Evidence thus indicates that in T. cruzi epimastigotes, L-glutamate controls cyclic GMP levels through a pathway mediated by nitric oxide.