Differences and similarities between COVID-19 related-headache and COVID-19 vaccine related-headache. A case-control study

INTRODUCTION

Headache is a frequent symptom at the acute phase of coronavirus disease 2019 (COVID-19) and also one of the most frequent adverse effects following vaccination. In both cases, headache pathophysiology seems linked to the host immune response and could have similarities. We aimed to compare the clinical phenotype and the frequency and associated onset symptoms in patients with COVID-19 related-headache and COVID-19 vaccine related-headache.

SUBJECTS AND METHODS

A case-control study was conducted. Patients with confirmed COVID-19 infection and COVID-19-vaccine recipients who experienced new-onset headache were included. A standardised questionnaire was administered, including demographic variables, prior history of headaches, associated symptoms and headache-related variables. Both groups were matched for age, sex, and prior history of headache. A multivariate regression analysis was performed.

RESULTS

A total of 238 patients fulfilled eligibility criteria (143 patients with COVID-19 related-headache and 95 subjects experiencing COVID-19 vaccine related-headache). Patients with COVID-19 related-headache exhibited a higher frequency of arthralgia, diarrhoea, dyspnoea, chest pain, expectoration, anosmia, myalgia, odynophagia, rhinorrhoea, cough, and dysgeusia. Further, patients with COVID-19 related-headache had a more prolonged daily duration of headache and described the headache as the worst headache ever experienced. Patients with COVID-19 vaccine-related headache, experienced more frequently pain in the parietal region, phonophobia, and worsening of the headache by head movements or eye movements.

CONCLUSION

Headache caused by SARS-CoV-2 infection and COVID-19 vaccination related-headache have more similarities than differences, supporting a shared pathophysiology, and the activation of the innate immune response. The main differences were related to associated symptoms.

α-Synuclein Drives Tau's Cytotoxic Aggregates Formation through Hydrophobic Interactions

Tau and α-synuclein are proteins involved in pathologies known as tauopathies and synucleinopathies, respectively. Moreover, evidence shows that there is a crosstalk between them as is seen in the brains of individuals with sporadic neurodegenerative disorders. Based on that, we present data showing that the hydrophobic α-peptide 71 VTGVTAVAQKTV82 induces the aggregation of the full-length tau fragment in the absence of heparin assessed by ThT. Moreover, AFM images reveal the presence of straight filaments and amorphous aggregates of full-length tau in the presence of the α-peptide. Additionally, ITC experiments showed the interaction of the α-peptide with tau full-length (441 amino acids),4R (amino acids from 244 to 369), and both hexapeptides 275 VQIINK280 and 306 VQIVYK311 through hydrophobic interactions. The Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. Furthermore, the incubation of extracellular aggregates with N2a cells showed morphological differences in the cellular body and the nucleus suggesting cell death. Moreover,, the incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH). Altogether, we found that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.

Bringing the Spotlight to tau and TDP-43 in Frontotemporal Dementia: A Review of Promising Chemical Compounds

There is a wide variety of neurodegenerative diseases, among which frontotemporal dementia stands out. These are the second most frequent cause of dementia in the world and demand the search for an effective treatment. This disease is linked to the abnormal behavior of proteins, which group together to form insoluble aggregates. It has been shown that the tau protein and TDP-43 are the main proteins involved in these pathologies. This article details 11 compounds already used in different neuropathologies, which may serve as potential drugs against these proteins. The mechanism of how most of these molecules inhibited the tau and TDP-43 aggregation process was highlighted. Importantly is to mention that Curcumin, Proanthocyanidin B2, Oleocanthal, Oleuropein Aglycone, Thionine, Resveratrol had been reported as direct inhibitors of tau. While 4-aminoquinoline, Dimethoxycurcumin, and Auranofin directly inhibited TDP-43. Epigallocatechin-3- gallate and Methylene Blue were described as tau and TDP-43 inhibitors. In this review, it is proposed that future research could elucidate the detailed inhibition mechanisms of these compounds to obtain relevant data to advance in treatments search for these coexisting proteins in frontotemporal dementia.

Dammarane triterpenes targeting α-synuclein: biological activity and evaluation of binding sites by molecular docking

Parkinson's disease (PD) is a neurodegenerative disorder that affects adult people whose treatment is palliative. Thus, we decided to test three dammarane triterpenes 1, 1a, 1b, and we determined that 1 and 1a inhibit β-aggregation through thioflavine T rather than 1b. Since compound 1 was most active, we determined the interaction between α-synuclein and 1 at 50 µM (Kd) through microscale thermophoresis. Also, we observed differences in height and diameter of aggregates, and α-synuclein remains unfolded in the presence of 1. Also, aggregates treated with 1 do not provoke neurites' retraction in N2a cells previously induced by retinoic acid. Finally, we studied the potential sites of interaction between 1 with α-synuclein fibrils using molecular modelling. Docking experiments suggest that 1 preferably interact with the site 2 of α-synuclein through hydrogen bonds with residues Y39 and T44.

The Fumarprotocetraric Acid Inhibits Tau Covalently, Avoiding Cytotoxicity of Aggregates in Cells

Neurodegenerative disorders, including Tauopathies that involve tau protein, base their pathological mechanism on forming proteinaceous aggregates, which has a deleterious effect on cells triggering an inflammatory response. Moreover, tau inhibitors can exert their mechanism of action through noncovalent and covalent interactions. Thus, Michael's addition appears as a feasible type of interaction involving an α, β unsaturated carbonyl moiety to avoid pathological confirmation and further cytotoxicity. Moreover, we isolated three compounds from Antarctic lichens Cladonia cariosa and Himantormia lugubris: protolichesterinic acid (1), fumarprotocetraric acid (2), and lichesterinic acid (3). The maleimide cysteine labeling assay showed that compounds 1, 2, and 3 inhibit at 50 µM, but compounds 2 and 3 are statistically significant. Based on its inhibition capacity, we decided to test compound 2 further. Thus, our results suggest that compound 2 remodel soluble oligomers and diminish β sheet content, as demonstrated through ThT experiments. Hence, we added externally treated oligomers with compound 2 to demonstrate that they are harmless in cell culture. First, the morphology of cells in the presence of aggregates does not suffer evident changes compared to the control. Additionally, the externally added aggregates do not provoke a substantial LDH release compared to the control, indicating that treated oligomers do not provoke membrane damage in cell culture compared with aggregates alone. Thus, in the present work, we demonstrated that Michael's acceptors found in lichens could serve as a scaffold to explore different mechanisms of action to turn tau aggregates into harmless species.

The Cytotoxic Effect of α-Synuclein Aggregates

Parkinson's disease is a neurodegenerative disorder involving a functional protein, α-synuclein, whose primary function is related to vesicle trafficking. However, α-synuclein is prone to form aggregates, and these inclusions, known as Lewy bodies, are the hallmark of Parkinson's disease. α-synuclein can alter its conformation and acquire aggregating capacity, forming aggregates containing β-sheets. This protein's pathogenic importance is based on its ability to form oligomers that impair synaptic transmission and neuronal function by increasing membrane permeability and altering homeostasis, generating a deleterious effect over cells. First, we establish that oligomers interfere with the mechanical properties of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membrane, as demonstrated by nanoindentation curves. In contrast, nanoindentation revealed that the α-synuclein monomer's presence leads to a much more resistant lipid bilayer. Moreover, the oligomers' interaction with cell membranes can promote lactate dehydrogenase (LDH) release, suggesting the activation of cytotoxic events.

Isolation, Gastroprotective Effects and Untargeted Metabolomics Analysis of Lycium Minutifolium J. Remy (Solanaceae)

Lycium minutifolium J. Remy (Solanaceae) is commonly used as an infusion in traditional medicine to treat stomach pain, meteorism, intestinal disorders, stomach ailments, and other severe problems including prostate cancer and stomach cancer. From the EtOAc extract of L. minutifolium bark five known metabolites were isolated using chromatographic techniques. The gastroprotective effects of the EtOAc fraction and edible infusion extract of the bark were assayed on the hydrochloric acid (HCl)/EtOH induced gastric ulcer model in mice to support the traditional use of the plant. The EtOAc extract and the edible infusion showed gastroprotective effect at dose of 100 mg/kg reducing lesions by 31% and 64%, respectively. The gastroprotective action mechanisms of the edible infusion at a single oral dose of 100 mg/kg were evaluated suggesting that prostaglandins, sulfhydryl groups, and nitric oxide are involved in the mode of gastroprotective action. The UHPLC analysis coupled to high-resolution mass spectrometry of the edible infusion showed the presence of twenty-three compounds. Our results can support the gastroprotective properties of the edible infusion extract, and at least can validate in part, the ethnopharmacological uses of the plant.

Comprehensive Kinetics of Hydrolysis of Organotriethoxysilanes by 29Si NMR

The kinetics of several representative hybrid precursors were studied via ²⁹Si NMR: three alkyl precursors, methyltriethoxysilane, ethyltriethoxysilane, and propyltriethoxysilane; as well as two unsaturated radicals, vinyltriethoxysilane and phenyltriethoxysilane. The reaction rate is related to the chemical shift of ²⁹Si in the NMR spectra, which gives information about the electronic density of the Si atoms and the inductive effects of substituents. The concentration of the precursors decreased exponentially with time, and the intermediate products of hydrolysis and the beginning of the condensation reactions showed curves characteristic of sequential reactions, with a similar distribution of the species as a function of the fractional conversion. For all of the precursors, condensation started when the most hydrolyzed species reached a maximum concentration of 0.30 M, when the precursor had run out. A prediction following the developed mathematical model fits the experimental results in line with a common pathway described by eight parameters.

Anthraquinone Derivative Reduces Tau Oligomer Progression by Inhibiting Cysteine-Cysteine Interaction

Tau protein is a natively unfolded protein whose primary role is to participate in axonal transport closely associated with microtubules. Neurodegenerative disorders including Alzheimer's disease and Tauopathies involved tau protein that is found hyperphosphorylated in vivo; then, tau is detached from microtubules to form toxic aggregates or oligomers, which have a deleterious effect on membranes, triggering an inflammatory response. Considering finding tau inhibitors, we isolated two compounds in the ethyl acetate extract from Xanthoria ectaneoides (Nyl.) Zahlbr; ergosterol peroxide (1) and a new anthraquinone (2). We established the structure through spectroscopic data and biogenic considerations, and we named it "2-hydroxy-3-((8-hydroxy-3-methoxy-6-methylanthraquinonyl)oxy)propanoic acid". This new anthraquinone was evaluated as a tau inhibitor by ThT fluorescence, dot blot assays and total internal reflection fluorescence microscopy. Our results strongly suggest that this anthraquinone remodels soluble oligomers and diminishes β-sheet content. Moreover, through the fluorescence labeling of cysteine inside of the microtubule-binding domain (4R), we showed that this anthraquinone could reduce the oligomers progression by inhibiting cysteine interactions.

Continental and Antarctic Lichens: isolation, identification and molecular modeling of the depside tenuiorin from the Antarctic lichen Umbilicaria antarctica as tau protein inhibitor

Alzheimer´s disease (AD) is the most common form of dementia involving Aβ and tau protein. So far, AD cure remains elusive, but considering that AD progresses throughout tau pathology, which turns tau protein an appropriate target, besides tau is also included in other neurodegenerative disorders named as tauopathies. Here, we have isolated seventeen compounds belonging to six lichens species. Due to scarce of spectroscopic data of the compound 5,7-dihydroxy-6-methylphthalide, we explained their structural elucidation based on NMR data. In this study, we show that only tenuiorin from Umbilicaria antarctica inhibited 50% of tau 4R at 100 µM. Then, we shown that molecular interactions of tenuiorin with the steric zipper model of the hexapeptide ³⁰⁶VQIVYK³¹¹ were studied by docking calculations and the results suggested that tenuiorin forms both hydrogen bonds with lysine and glutamine side chains and forms several hydrophobic interactions with valine and lysine from ³⁰⁶VQIVYK³¹¹ motif.

Silica coated iron nanoparticles: synthesis, interface control, magnetic and hyperthermia properties

This work provides a detailed study on the synthesis and characterization of silica coated iron nanoparticles (NPs) by coupling Transmission Electronic Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and magnetic measurements. Remarkably, iron NPs (of 9 nm of mean diameter) have been embedded in silica without any alteration of the magnetization of the iron cores, thanks to an original protocol of silica coating in non alcoholic medium. Tuning the synthesis parameters (concentration of reactants and choice of solvent), different sizes of Fe@SiO₂ composites can be obtained with different thicknesses of silica. The magnetization of these objects is fully preserved after 24 h of water exposure thanks to a thick (14 nm) silica layer, opening thus new perspectives for biomedical applications. Hyperthermia measurements have been compared between Fe and Fe@SiO₂ NPs, evidencing the self-organization of the free Fe NPs when a large amplitude magnetic field is applied. This phenomenon induces an increase of heating power which is precluded when the Fe cores are immobilised in silica. High-frequency hysteresis loop measurements allowed us to observe for the first time the increase of the ferrofluid susceptibility and remanence which are the signature of the formation of Fe NPs chains.

A novel method has been developed for the silica coating of iron nanoparticles while preserving the magnetic properties.

Secondary Metabolite Profiling of Species of the Genus Usnea by UHPLC-ESI-OT-MS-MS

Lichens are symbiotic associations of fungi with microalgae and/or cyanobacteria, which are considered among the slowest growing organisms, with strong tolerance to adverse environmental conditions. There are about 400 genera and 1600 species of lichens and those belonging to the Usnea genus comprise about 360 of these species. Usnea lichens have been used since ancient times as dyes, cosmetics, preservatives, deodorants and folk medicines. The phytochemistry of the Usnea genus includes more than 60 compounds which belong to the following classes: depsides, depsidones, depsones, lactones, quinones, phenolics, polysaccharides, fatty acids and dibenzofurans. Due to scarce knowledge of metabolomic profiles of Usnea species (U. barbata, U. antarctica, U. rubicunda and U. subfloridana), a study based on UHPLC-ESI-OT-MS-MS was performed for a comprehensive characterization of their secondary metabolites. From the methanolic extracts of these species a total of 73 metabolites were identified for the first time using this hyphenated technique, including 34 compounds in U. barbata, 21 in U. antarctica, 38 in U. rubicunda and 37 in U. subfloridana. Besides, a total of 13 metabolites were not identified and reported so far, and could be new according to our data analysis. This study showed that this hyphenated technique is rapid, effective and accurate for phytochemical identification of lichen metabolites and the data collected could be useful for chemotaxonomic studies.

Rosmarinic acid prevents fibrillization and diminishes vibrational modes associated to β sheet in tau protein linked to Alzheimer's disease

Alzheimer's disease is a common tauopathy where fibril formation and aggregates are the hallmark of the disease. Efforts targeting amyloid-β plaques have succeeded to remove plaques but failed in clinical trials to improve cognition; thus, the current therapeutic strategy is at preventing tau aggregation. Here, we demonstrated that four phenolic diterpenoids and rosmarinic acid inhibit fibrillization. Since, rosmarinic acid was the most active compound, we observe morphological changes in atomic force microscopy images after treatment. Hence, rosmarinic acid leads to a decrease in amide regions I and III, indicating that rosmarinic acid prevents β-sheet assembly. Molecular docking study inside the steric zipper model of the hexapeptide 306VQIVYK311 involved in fibrillization and β sheet formation, suggests that rosmarinic acid binds to the steric zipper with similar chemical interactions with respect to those observed for orange G, a known pharmacofore for amyloid.

The Polyphenol Altenusin Inhibits in Vitro Fibrillization of Tau and Reduces Induced Tau Pathology in Primary Neurons

In Alzheimer's disease, the microtubule-associated protein tau forms intracellular neurofibrillary tangles (NFTs). A critical step in the formation of NFTs is the conversion of soluble tau into insoluble filaments. Accordingly, a current therapeutic strategy in clinical trials is aimed at preventing tau aggregation. Here, we assessed altenusin, a bioactive polyphenolic compound, for its potential to inhibit tau aggregation. Altenusin inhibits aggregation of tau protein into paired helical filaments in vitro. This was associated with stabilization of tau dimers and other oligomers into globular structures as revealed by atomic force microscopy. Moreover, altenusin reduced tau phosphorylation in cells expressing pathogenic tau, and prevented neuritic tau pathology induced by incubation of primary neurons with tau fibrils. However, treatment of tau transgenic mice did not improve neuropathology and functional deficits. Taken together, altenusin prevents tau fibrillization in vitro and induced tau pathology in neurons.

Secondary Metabolites in Ramalina terebrata Detected by UHPLC/ESI/MS/MS and Identification of Parietin as Tau Protein Inhibitor

Liquid chromatography coupled with mass spectrometry is an outstanding methodology for fast analysis of phenolic compounds in biological samples. Twenty two compounds were quickly and accurately identified in the methanolic extract of the Antarctic lichen Ramalina terebrata for the first time using ultra high pressure liquid chromatography coupled with photodiode array detector and high resolution mass spectrometry (UHPLC-PDA-Q/Orbitrap/MS/MS). In addition, the extract and the four compounds isolated from this species were tested for the inhibitory activity of tau protein aggregation, which is a protein involved in Alzheimer's disease (AD). All compounds showed null activity with the exception of parietin, which it was able to inhibit aggregation process of tau in a concentration range between 3 µg/mL (10 µM) to 28 µg/mL (100 µM). In addition, we show how parietin interact with tau (306)VQIVYK(311) hexapeptide inside of the microtubule binding domain (4R) with the help of molecular docking experiments. Finally, the constituents present in the methanolic extract could possibly contribute to the established anti-aggregation activity for this extract and this in-depth analysis of the chemical composition of R. terebrata could guide further research into its medicinal properties and potential uses.

Seco-taondiol, an unusual meroterpenoid from the Chilean seaweed Stypopodium flabelliforme and its gastroprotective effect in mouse model

Ten known meroterpenoids and the new meroterpenoid 7 were isolated from the Chilean seaweed Stypopodium flabelliforme as their acetylated derivatives. Furthermore, the known metabolite taondiol has been isolated for the first time from this species. The molecular structure of the new metabolite was determined by spectroscopic methods based on 1D- and 2D-NMR. Isolation of 7 represents a key step toward a better understanding of the biogenesis of this class of meroterpenoids. Among the meroditerpenoids isolated, stypodiol, isoepitaondiol, epitaondiol and sargaol exhibited gastroprotective activity on the HCl/Ethanol-induced gastric lesions model in mice. Regarding the mode of gastroprotective action, the activity of epitaondiol was reversed significantly when animals were pretreated with indomethacin, N-ethylmaleimide and N-nitro-l-arginine methyl ester (L-NAME) suggesting that prostaglandins, sulfhydryl groups and nitric oxide are involved in their mode of gastroprotective action. In the case of sargaol the gastroprotective activity was attenuated with indomethacin and N-ethylmaleimide, which suggests that prostaglandins and sulfhydryl groups are also involved in the mode of action using this model.

From rational design of organometallic precursors to optimized synthesis of core/shell Ge/GeO2 nanoparticles

The synthesis conditions of germanium-based nanoparticles have been drastically softened thanks to the design of a suitable precursor featuring enhanced reactivity.

Neoplastic zebras of venous thrombosis: Diagnostic challenges in vascular medicine

Venous thrombosis is a common medical problem. Imaging differentiation of neoplasms and venous clots may prove challenging. We report three cases of "mistaken identities" of venous thrombi and neoplasms on the basis of clinical findings and different imaging modalities: ultrasound, computed tomography, and magnetic resonance imaging. Imaging studies are not always reliable and consideration of clinical features, including pretest probability, is necessary for correct diagnosis. A combination of imaging modalities and biopsies is needed for correct diagnosis in some cases.

A novel monoclonal antibody against the C-terminus of β-tubulin recognizes endocytic organelles in Trypanosoma cruzi

Microtubule cytoskeleton is a dynamic structure involved in the maintenance of eukaryote cell shape, motion of cilia and flagellum, and intracellular movement of vesicles and organelles. Many antibodies against tubulins have been described, most of them against the C-terminal portion, which is exposed at the outside of the microtubules. By generating a novel set of monoclonal antibodies against the cytoskeleton of Trypanosoma cruzi, a flagellate protozoan that causes Chagas' disease, we selected a clone (mAb 3G4) that recognizes β-tubulin. The epitope for mAb 3G4 was mapped by pepscan to a highly conserved sequence motif found between α-helices 11 and 12 of the C-terminus of β-tubulin in eukaryotes. It labels vesicular structures in both T. cruzi and mammalian cells, colocalizing respectively with a major cysteine protease (Cruzipain) and lysosome associated protein (LAMP2) respectively, but it does not label regular microtubules on these cellular models. We propose that the epitope recognized by mAb 3G4 is exposed only in a form of tubulin associated with endosomes.

Fulvic acid inhibits aggregation and promotes disassembly of tau fibrils associated with Alzheimer's disease

Alzheimer's disease is a neurodegenerative disorder involving extracellular plaques (amyloid-β) and intracellular tangles of tau protein. Recently, tangle formation has been identified as a major event involved in the neurodegenerative process, due to the conversion of either soluble peptides or oligomers into insoluble filaments. At present, the current therapeutic strategies are aimed at natural phytocomplexes and polyphenolics compounds able to either inhibit the formation of tau filaments or disaggregate them. However, only a few polyphenolic molecules have emerged to prevent tau aggregation, and natural drugs targeting tau have not been approved yet. Fulvic acid, a humic substance, has several nutraceutical properties with potential activity to protect cognitive impairment. In this work we provide evidence to show that the aggregation process of tau protein, forming paired helical filaments (PHFs) in vitro, is inhibited by fulvic acid affecting the length of fibrils and their morphology. In addition, we investigated whether fulvic acid is capable of disassembling preformed PHFs. We show that the fulvic acid is an active compound against preformed fibrils affecting the whole structure by diminishing length of PHFs and probably acting at the hydrophobic level, as we observed by atomic force techniques. Thus, fulvic acid is likely to provide new insights in the development of potential treatments for Alzheimer's disease using natural products.

Calcineurin B of the human protozoan parasite Trypanosoma cruzi is involved in cell invasion

During Trypanosoma cruzi cell invasion, signal transduction pathways are triggered in parasite and host cells, leading to a rise in intracellular Ca2+ concentration. We posed the question whether calcineurin (CaN), in particular the functional regulatory subunit CaNB, a Ca2+-binding EF-hand protein, was expressed in T. cruzi and whether it played a role in cell invasion. Here we report the cloning and characterization of CL strain CaNB gene, as well as the participation of CaNB in cell invasion. Treatment of metacyclic trypomastigotes (MT) or tissue-culture trypomastigotes (TCT) with the CaN inhibitors cyclosporin or cypermethrin strongly inhibited (62-64%) their entry into HeLa cells. In assays using anti-phospho-serine/threonine antibodies, a few proteins of MT were found to be dephosphorylated in a manner inhibitable by cyclosporin upon exposure to HeLa cell extract. The phosphatase activity of CaN was detected by a biochemical approach in both MT and TCT. Treatment of parasites with antisense phosphorothioate oligonucleotides directed to TcCaNB-CL, which reduced the expression of TcCaNB and affected TcCaN activity, resulted in approximately 50% inhibition of HeLa cell entry by MT or TCT. Given that TcCaNB-CL may play a key role in cell invasion and differs considerably in its primary structure from the human CaNB, it might be considered as a potential chemotherapeutic target.

Pybox Monolithic Miniflow Reactors for Continuous Asymmetric Cyclopropanation Reaction under Conventional and Supercritical Conditions

Supported catalysts having pybox chiral moieties were prepared as macroporous monolithic miniflow systems. These catalysts are based on styrene-divinylbenzene polymeric backbones having different compositions and pybox chiral moieties. Their corresponding ruthenium complexes were tested for the continuous flow cyclopropanation reaction between styrene and ethyldiazoacetate (EDA) under conventional conditions and in supercritical carbon dioxide (scCO2). Ru-Pybox monolithic miniflow reactors not only provided a highly efficient and robust heterogeneous chiral catalyst but also allowed us to develop more environmental reaction conditions without sacrificing the global efficiency of the process.

Construction of a frameless camera-based stereotactic neuronavigator

We built an infrared vision system to be used as the real time 3D motion sensor in a prototype low cost, high precision, frameless neuronavigator. The objective of the prototype is to develop accessible technology for increased availability of neuronavigation systems in research labs and small clinics and hospitals. We present our choice of technology including camera and IR emitter characteristics. We describe the methodology for setting up the 3D motion sensor, from the arrangement of the cameras and the IR emitters on surgical instruments, to triangulation equations from stereo camera pairs, high bandwidth computer communication with the cameras and real time image processing algorithms. We briefly cover the issues of camera calibration and characterization. Although our performance results do not yet fully meet the high precision, real time requirements of neuronavigation systems we describe the current improvements being made to the 3D motion sensor that will make it suitable for surgical applications.

A novel protein phosphatase 2A (PP2A) is involved in the transformation of human protozoan parasite Trypanosoma cruzi

Here we provide evidence for a critical role of PP2As (protein phosphatase 2As) in the transformation of Trypanosoma cruzi. In axenic medium at pH 5.0, trypomastigotes rapidly transform into amastigotes, a process blocked by okadaic acid, a potent PP2A inhibitor, at concentrations as low as 0.1 microM. 1-Norokadaone, an inactive okadaic acid analogue, did not affect the transformation. Electron microscopy studies indicated that okadaic acid-treated trypomastigotes had not undergone ultrastructural modifications, reinforcing the idea that PP2A inhibits transformation. Using a microcystin-Sepharose affinity column we purified the native T. cruzi PP2A. The enzyme displayed activity against 32P-labelled phosphorylase a that was inhibited in a dose-dependent manner by okadaic acid. The protein was also submitted to MS and, from the peptides obtained, degenerate primers were used to clone a novel T. cruzi PP2A enzyme by PCR. The isolated gene encodes a protein of 303 amino acids, termed TcPP2A, which displayed a high degree of homology (86%) with the catalytic subunit of Trypanosoma brucei PP2A. Northern-blot analysis revealed the presence of a major 2.1-kb mRNA hybridizing in all T. cruzi developmental stages. Southern-blot analysis suggested that the TcPP2A gene is present in low copy number in the T. cruzi genome. These results are consistent with the mapping of PP2A genes in two chromosomal bands by pulsed-field gel electrophoresis and chromoblot hybridization. Our studies suggest that in T. cruzi PP2A is important for the complete transformation of trypomastigotes into amastigotes during the life cycle of this protozoan parasite.

[Survival of patients with esophageal cancer subjected to total thoracic esophagectomy]

BACKGROUND

Esophageal carcinoma has a dismal prognosis. Several authors have reported a very low survival in Chile.

AIM

To report the survival of patients with esophageal carcinoma, subjected to esophageal resection.

MATERIAL AND METHODS

Analysis of 108 patients subjected to thoracic esophageal resection between 1985 and 1996. Patients were classified according to the location of the tumor and its staging.

RESULTS

Eleven patients died in the immediate postoperative period and 90 patients were followed. In 53 the exact cause of death was determined. Global five years survival was 29% and median survival was 18 months. Survival was 100% in stage I tumors. Adjuvant therapy resulted in a better survival of stage III tumors. Survival of stage IV tumors was worst than stage I to III tumors. There was no survival difference between squamous carcinoma or adenocarcinoma. Tumors located in the superior third of the esophagus had a worst prognosis. Causes of death were mediastinic metastases, local recidivism, pleural or pulmonary metastases and less frequently, brain, bronchial or bone metastases.

CONCLUSIONS

The survival of these, patients with esophageal carcinoma did not differ from the figures reported abroad.

Analytical study of the optical parameters for a multiple-path telescope

A reflecting telescope arrangement is proposed in which the focal distance of the objective system is greatly enhanced without increasing the overall length of the structure. The underlying idea is to use a multiply folded optical path. This setup may be viewed as a partially periodic optical system. For small departures of the mirror confocality, analytic results in the paraxial approximation are obtained.

[Natural history of viral hepatitis A in Chilean adults: clinical and laboratory aspects]

In many countries, Hepatitis is mainly due to virus. A. When improving life condition in a given population, initially there is a tendency to increase the number of cases in adults. We report clinical and laboratory findings in 87 adults with acute viral Hepatitis A in Chile. The rate man/woman was 1.55/1. Mean age: 23.8 years. Clinical forms: icteric classical (77.01%), cholestatic (10.34%), anicteric (8.05%), biphasic (2.30%) and fulminant (2.30%). From 87 patients in consult 1, 64 were controlled at day 15 (consult 2) and 35 one year later (consult 3). Laboratory (means): ALT (UI/L): 856.8, 111.6 and 20.8 in consult 1, 2 and 3 respectively. Correlation between values of ALT and AST (p < 0.0001). Mean total bilirubin (mg%): 6.6, 2.5 and 0.8 respectively. The evolution of Hepatitis A was favorable with a rapid decrease of clinical signs and normalization of laboratory values within the 3 first weeks of disease.

Degenerative ultrastructural changes observed in the neuropil of caudate nuclei from Parkinson's disease patients

Degenerative changes of the pars compacta of the substantia nigra are considered the main physiopathological basis of Parkinson's disease, while most authors believe that the neostriatum is well preserved in these cases. This paper deals with the preliminary ultrastructural observations made in the neuropil of the caudate nucleus of Parkinson's disease patients. We have observed (1) astrocytic proliferation, neuronal degeneration, degenerated axons, and hyperdense postsynaptic neurites (dendrites), and (2) that degenerative patterns vary from one case to another. Physiopathological and therapeutical implications are discussed.

Multidisciplinary analysis of the effectiveness of autologous neural transplant (adrenal medulla) as treatment of Parkinson's disease

The neurobiological aspects of human neural transplants are far from being understood. We have approached their study by means of a multidisciplinary working team. Nine patients with Parkinson's disease were subjected to open brain surgery for grafting of autologous adrenal medulla. Not all patients improved. Those patients that did so showed different patterns of improvement. Rigidity was the sign most relieved in this group of patients. Electroencephalographic changes were attributable to surgical manipulation. High-performance liquid chromatographic quantification of catecholaminergic metabolites did not correlate with post-grafting outcome. Biopterin levels showed a significant increment after surgery. More interdisciplinary studies ought to be done on neural transplants.

Cardiac arrhythmias in experimental subarachnoid hemorrhage

Experimental subarachnoid hemorrhage (SAH) in dogs was produced by introducing blood into the subarachnoid space through a catheter connected to an artery of the animal. The intact animals and those with preserved vagi and heart sympathetic innervation, developed arrhythmias with short latencies which correlated with the sudden increase in the intracranial pressure. The animals with sections of both vagi and heart sympathetic innervation, but with an intact spinal cord, developed arrhythmias that were delayed and did not correlate with the changes in intracranial pressure. These arrhythmias were preceded by changes in the QT interval, T wave and ST segment. It was concluded that the arrhythmias could be produced either by direct autonomic discharges to the heart or by increased circulating and tissue catecholamines. The clinical implications of these findings are discussed.

Side band Ronchi test

Using holographic techniques a Ronchi ruling with carrier may be generated which has the property of giving highly defined Ronchi fringes, instead of the diffraction-blurred fringes produced in the normal test. This procedure can be generalized to include the case of circular fringes.

Bibliography of various optical testing methods

A bibliography of various methods of optical testing has been compiled, with the papers grouped by subject, e.g., Fizeau interferometer. Only interferometer papers-or those on similar devices-that have direct relevance to shop testing are included. This reasonably complete compendium should be of use to workers in optical fabrication and testing.

Null ronchi test for aspherical surfaces

A new kind of null Ronchi test for aspherical surfaces is devised using a special ruling with curved lines. This test is found to be more advantageous for aspherical surfaces that the normal Ronchi test, which depends solely on computation to determine the shape of the fringes on the surface. The only restriction on this test is that a point source must be used.